'Sourecha Training ni Naranai de Sho!?' Yaseru made Zenshin Undou de Asedaku Piston!

Akari Nishimori, on the advice of her childhood friend Hayato Takahashi, joins a gym to try to lose some weight. Despite feeling self-conscious in the sports bra, she resolves to stick to her diet. However, her exercise routine takes an unexpected turn when her breasts unexpectedly fall out shortly after beginning her workout. Hayato's actions escalate as he insists that his behavior is a training regimen known as "sexercise," gradually increasing the intensity until Akari is left feeling overwhelmed. As the situation spirals out of control, Akari becomes aware of a new, unfamiliar sensation - something hard is twitching against her body, leaving her uncertain about what is happening.