WARNING: The following contains spoilers for Episode 10 of Tropical-Rouge! Precure, "Combined Motivation! Pretty Cure Mix Tropical!" now streaming on Crunchyroll.
Following the ominous threads of the previous episode, in Episode 10, "Combined Motivation! Pretty Cure Mix Tropical!," of Tropical-Rouge! Precure, the Cures soon find themselves up against a Zenzen Yarane-da. Manatsu allows the day's stresses to overcome her better judgment and attacks before reclaiming the stolen motivation. This huge mistake not only prolongs the battle but makes Manatsu herself susceptible to the Yarane-da's thievery, robbing her of her motivation and ability to become Cure Summer.
But how could Manatsu, the girl overflowing with motivation, lose it entirely? To understand that, we have to examine Manatsu's circumstances before the battle with Chiron-ge even began.
The episode opens with the not-quite-revelation that Manatsu, like many main Cures before her, is not the best at her studies, having failed a test. While this in and of itself is not too big a blow, Asuka quickly points out that, should Manatsu fail the upcoming tests, the Tropical Club will be suspended, which definitely gets Manatsu's anxiety up. Thus, when she gets home she commits herself to study... for all of thirty seconds. Not actually wanting to do it, Manatasu procrastinates, cleaning up her workspace and reviewing a dessert magazine instead of putting pencil to paper. This highlights an aspect of Manatsu's personality that is both her greatest strength and biggest flaw: her impulsiveness.
While Manatsu often uses her impulsive nature positively, taking others on adventures, learning about things and being adaptable to the situation, her stress causes its more negative side to take hold. She becomes easily distracted, impatient and rushes through tasks. It is these last two that cause her to lose her judgment in battle.
In previous fights, it's been implied that the girls shouldn't use their "finishing move" on the Yarane-da until Laura has reclaimed the stolen motivation. In Episode 6, "It Starts Now! The Tropical Club!," upon hearing that no motivation was stolen, Flamingo remarks "No need to hold back then." Whether this is because the monster is just inherently stronger before the motivation is removed, or because the motivation would be destroyed along with the monster is never elaborated on. The fact remains that the Zenzen Yarane-da that the girls encounter in Episode 10 has stolen plenty of motivation by the time they reach it.
Ironically, it is her listless state that helps motivate the other girls. Despite being entirely overwhelmed by the Yarane-da, Flamingo, Papaya and Coral are relentless in their defense of their friend. When given a brief respite, the girls do everything they can to re-motivate the exhausted Manatsu, offering to paint her nails, lend her a fun book and eat mango-flavored melon bread together. However, their attempts seem futile as Manatsu only wants to sleep -- until Chiron-ge and the Zenzen Yarane-da return.
While she may not be able to keep her eyes open entirely, Manatsu still sees and hears her friends battling as hard as they can -- and her friendship and a strong sense of justice draw her back to her feet as she shambles back onto the battlefield to protect her team. She herself, however, is a sitting duck, and the others are blasted back by a powerful attack as they jump to save her. Seeing this apparent defeat only solidifies Manatsu's resolve, and her righteous fury reignites her motivation, allowing her to become Cure Summer once more!
Manatsu is already back at full strength when Laura returns the stolen motivation -- meaning that Manatsu's original motivation is able not only to return to and strengthen her but overflows to the others as well, allowing them to create the titular finisher, Mix Tropical.
While Manatsu's impatience nearly spelled defeat for her and her team, she's learned a valuable lesson about patient persistence and doing tasks properly, while the villains have learned that the Cures are ready to step up to any new power they throw at them.