Tropical-Rouge! Pretty Cure

Manatsu Natsuumi, an energetic girl, moves to Aozora City from Minamino Island to live with her mother, who works at the city's aquarium. Meanwhile, in the Grand Ocean Kingdom, Laura, a mermaid, is tasked to find humans who can open her assigned Tropical Pact to fight back against the Witch of Procrastination. Following the Mermaid Queen's orders, Laura heads off to Aozora City. Meanwhile, Manatsu arrives at the city, reunites with her mother and explores the city area and aquarium. While taking a break, Laura and Manatsu encounter each other with the mermaid explaining her mission while secretly intending to complete it for her own agenda. Later, a crab general of the Witch named Chongire arrives and creates a monster, a Yaraneeda, from a coconut tree to steal Motivation Power from a group of runners at a beach. Alerted by a strange energy field in an area of the city, Manatsu heads off to confront the monster, believing Laura was in danger. When Laura gets captured, Manatsu resolves to immediately do the most important thing. As a result, Laura's assigned compact opens and grants Manatsu the power to become one of the legendary warriors, the Pretty Cure, foretold in the Grand Ocean's legends. With this new power, Manatsu, now as Cure Summer, defeats the monster and rescues Laura who salvages and returns the stolen Motivation Power. After the battle, Laura and Manatsu befriend each other. Meanwhile, the Witch of Procrastination is notified of the Pretty Cure's appearance, but decides to address the issue later.

While Laura intends to find more humans who can open her three remaining pacts, Manatsu prepares for her first day in Aozora city's school. In her class, she recognises a girl she saw when she explored the city. The two girls befriend each other and discuss the school clubs they intend to join. Manatsu learns that her new friend, Sango Suzumura, desires to join the Cosmetics Club and runs a cosmetic shop along with her own mother, Miyuki Suzumura. However, Laura and Manatsu start a conflict among themselves, with Laura going in Manatsu's bathtub and the school's swimming pool to gain her friend's attention. As a result, the two leave each other after a quarrel. Laura, heading off to the city, encounters a reluctant Chongire making a Yaraneeda from a beach umbrella stand. Meanwhile, Manatsu begins to regret lashing out at Laura and rushes over to help her once she gets alerted of the Yaraneeda's rampage. Arriving to save the mermaid, Manatsu transforms to engage and defeat the Yaraneeda, with Laura returning the stolen Motivation Power. Afterwards, Laura and Manatsu reconcile, though the latter misses out on the school's club orientation.

Manatsu heads out on a weekend trip around Aozora City with a couple of her classmates including Sango. The group meets at the city's shopping mall where Manatsu is fascinated by the merchandise sold and Sango gives her purchased ice cream to a younger girl. The group then heads off to the aquarium where Sango is separated from them while trying to return a lost wallet. Sango then tries to search for her friends only to cross paths with Laura. The next day, Sango confides in Manatsu that she does not like standing out among others due to an incident back in kindergarten. Upon hearing her out, Laura encourages Sango to believe in her "cute". Later that day, Chongire summons a Yaraneeda to attack a park, forcing Manatsu to head off to transform and confront the monster. When Cure Summer and Laura get overpowered by the foe, Sango, who followed Manatsu to the battle, finally plucks up her courage to believe in her own choices. As a result, the second Tropical Pact opens, granting her the power to transform into Cure Coral who, with Laura and Cure Summer's help, defeats the Yaraneeda. After the battle, Manatsu and Sango become closer friends and resolve to do their best, even as Pretty Cures.

Manatsu and Sango discuss on what clubs to join, during which, Laura suggests making one themselves. As the two human girls do research for their own club at the school's library, they encounter a stoic bespectacled girl, Minori Ichinose, who does not believe in the existence of mermaids although she likes mermaid stories. Deciding to find out more about that girl, Sango and Manatsu discover that she is a top student in school. However, when they try to compliment her on a story she wrote, Minori, believing otherwise, turns down their praises, due to a past traumatic experience back when she was in the school's literature club. The next day, Minori meets Sango and Manatsu at an exhibition at the city's museum, and encounters Laura for the first time. Despite the others' encouragement, Minori timidly tries to back off. At that moment, a sea slug-like general of the Witch of Procrastination, Numeri, summons a Yaraneeda to terrorize the museum's courtyard. Manatsu and Sango transform to engage the monster only for the enemy to overwhelm them. Encouraged by Laura, Minori finally resolves to believe in herself. As a result, the third Tropical Pact grants Minori the power to become Cure Papaya who defeats the Yaraneeda with assistance from her friends. Afterwards, Minori, having broken her limits, befriends the trio.

Manatsu meets a new friend, ninth-grader Asuka Takizawa, and she and her friends decide to try recruiting her to become the fourth Pretty Cure, owing to Asuka's physical strength. However, Asuka is not interested, much to their chagrin. Meanwhile, Sango and Manatsu struggle to get their club started, with the issue compounded by the fact that there were very few clubrooms left. Asuka arrives to help them, though she does not intend to join their club. Later that day, Minori, Manatsu, Asuka and Sango clean up a packed room to use for their club, during which, Laura compliments Asuka and points out the latter's strengths. As such, Asuka, despite not truly believing in teamwork, begins to warm up to the others. Suddenly, Numeri appears and summons a Yaraneeda from a totem pole in the garbage. Manatsu, Sango and Minori to transform to engage the enemy but the monster proves to be a formidable foe and overpowers all three Cures and Laura. Asuka, alerted by the Yaraneeda's rampage, intervenes, resolving to protect her friends. As a result, the fourth and final Tropical Pact grants Asuka the power to become Cure Flamingo. All four Cures and Laura work together to defeat the Yaraneeda, with Cure Flamingo finishing the monster off. Afterwards, Asuka decides to believe in teamwork again, befriends the group and joins their club.

While the Witch of Procrastination and her butler discuss their plans and the Pretty Cure's interference, Manatsu and her friends discuss about their club activity. Manatsu, deciding to try everything, approaches student council president Yuriko Shiratori to initiate her club only to get rejected. As such, the four girls and Laura try out many ideas for their club, but are not satisfied with any of them. As they worry about the imminent club application deadline, the girls encounter a quartet of alumni students from their school looking for a penguin ornament. Remembering that they cleared out said ornament while cleaning up their clubroom, the girls head off to search for it, during which, they learned that a shop had taken it in. However, the penguin reacts with a dark orb it was housing, and turns into a Yaraneeda. In response, the girls transform to engage and quickly defeat the monster. Afterwards, the four girls return the penguin ornament to the alumni group and finally get their club application approved, Manatsu having officially decided on their club activity.

While jogging at the beach, Manatsu and her friends spot a seal, which Laura recognises as the Mermaid Queen's pet Kururun. The girls examine the seal with Laura misinterpreting its desires and Minori deducing that the seal was hungry. Minori also guesses that Kururun headed to the city from the Grand Ocean Kingdom to make a delivery for Laura but got swept by an ocean current. As such, the four girls and Laura search for Kururun's package with Minori finding it hanging on a tree branch due to another person finding said package and placing it there. Just then, a prawn general of the Witch, Elda, appears to intercept Kururun's delivery and summons a Yaraneeda to complete the task. As such, the four girls transform to engage the foe, during which, Laura discovers that the Queen sent her some treats. Despite Elda's taunts, Cure Papaya stands her ground and finishes the monster off, forcing Elda to retreat. Afterwards, the girls, Kururun and Laura bond over the goodies with the mermaid correctly deducing that Kururun was going to stay with her and the others.

 The four girls sit together for bento lunches, during which, Manatsu samples her friends' ingredients. Asuka then mentions how her family helps one another with the chores inspiring Manatsu to make a bento meal inspired from Kururun. As such, Asuka leads the other girls in making the meal with Laura assisting them with the cooking. Elsewhere, Chongire summons a Yareneeda to terrorize a mobile food stall and its surrounding area. The girls are alerted to the attack and transform to fight the monster but are hungry from not eating lunch and thus are overwhelmed by the enemy. As such, Asuka leads the others to freeze the monster and eat their meal before they return to defeat the foe. Afterwards, the girls enjoy their bentos together and Manatsu prepares dinner for herself and her mother.

The tropical club make preparations for their school when it is selected to be a film shooting location. Manatsu and her friends meet an actress named Yuna, who is insecure about her role and will have her makeup covered by Sango's mother. As such, the four girls train Yuna for her role while Sango is tasked to dress up into a mascot for Miyuki's beauty palor. Later, Manatsu's friends recount how Manatsu influenced them and Yuna takes over Sango's task once Sango wears out. However, Numeri arrives and summons a Yareneeda on the day of the filming, forcing Manatsu and her friends to transform to fight the foe. Cure Coral buys the other Cures time to grab some mirrors as part of Cure Papaya's plan to blind the monster with said mirrors and salvage its Motivation power before Cure Coral defeats it. Afterwards, the four girls and some more students get involved in the film while the Witch's forces are briefed on their latest plans.

Manatsu's friends postpone their club activities to study, with Manatsu revealing she is not good at it. Manatsu tries studying on her own, but finds herself struggling to do so. As such, her friends teach her how to study properly. At that moment, Chongire arrives and summons a stronger Yaraneeda variant called a Zenzen Yaraneeda to attack the school's yard. The girls transform to engage the enemy, but the monster proves to be a formidable foe which also overpowers Manatsu and saps her motivation. Laura's mermaid aqua pot also gets knocked away, forcing Laura to leave to search for it, while Asuka, Minori and Sango try to awaken Manatsu to no avail. When the Zenzen Yaraneeda returns, the three remaining girls transform to engage it again, only to get overpowered by the foe. However, Manatsu stands up to Chongire for her friends and is thus re-energized and motivated once again. Laura also returns, having found her jar, and gives the four Cures a new power; with that new power, the Cures execute Mix Tropical to finally defeat the monster. Afterwards, Manatsu reconciles with her friends and resolves to study harder with them, even though she reveals that she failed all of her school tests.

Manatsu and her friends discuss activities they can participate with the other school clubs with Minori suggesting sand art at the beach. As such, the four girls hold a sand art contest involving a great number of people in their school and participate in it as well. Over the course of the contest, Manatsu and her friends bond over making their own sand art. However, a heavy downpour occurs on the second day of the contest. Taking an idea from Laura as she looks through her photographs, Manatsu uses some parachute to protect the sand art pieces from the rain. At that moment, Numeri summons a Zenzen Yaraneeda to attack the beach, forcing the four girls to transform to engage it. The monster proves to be a tough enemy, but the Cures and Laura manage to counter and defeat the foe. Afterwards, everyone admires their sand artwork, including Manatsu and her friends even though they did not win. Later on, Laura confides in Manatsu of her loneliness over not being able to join any club activities they do. In response, Manatsu promises to find a club activity Laura can join in as well.

Manatsu and her friends are discussing on their next club activity when the school's disciplinary committee head, Masami Kakuta, searches the room owing to rumours of a mermaid sighting in the school. Upon learning on the search, Asuka confronts the disciplinary committee over the matter. The committee mentions a rule allowing them to confiscate suspicious items to maintain order in the school. The next day, rumours of a mermaid around and in school run rampant while Yuriko turns down Asuka's complaint and Masami almost spots Laura. Masami approaches the Tropical Club and confiscates the Aqua Pot. Later on, Elda summons a Zenzen Yaraneeda to attack a playground. Despite the other girls' worries, Laura encourages them to engage the enemy without her. The four girls transform to fight the monster but struggle against it. Meanwhile, Laura sneaks around school and reclaims her pot while evading Masami. She then returns to the Cures to salvage the Zenzen Yaraneeda's stolen motivation power, allowing the four Cures to finish it off. Afterwards, the disciplinary committee confronts the Tropical Club about the Aqua Pot, but Asuka and Minori assert its importance to the club citing another rule and revealing their teacher approved of it before the committee leaves taking a worn out Masami with them.

When the school's public announcement mentions the rumors of a mermaid, Manatsu and her friends discuss folklore concerning mermaids, with Laura stating of their singing talents. Later on, the four girls meet members of the broadcasting club and offer their aid. On the day of the broadcasting, one of the hosts is unable to join the others, forcing Manatsu and her friends to host the broadcast instead. The four girls end up struggling to carry on the show. Thankfully, Laura salvages the situation by pretending to be an interviewee. Meanwhile, Chongire summons a Zenzen Yaraneeda to attack a supermarket, forcing the four girls to leave Laura to finish the job while they head off to transform and confront the monster. All four Cures struggle to engage the foe until Laura finishes the broadcast and hurries over to assist them in defeating the monster. The next day, the broadcasting club receive requests of wanting to hear Laura sing again, much to the girls' joy.