Taishi Kawasaki

Driven by suspicion regarding his older sister Saki's mysterious nighttime habits, this determined younger brother seeks the group's assistance to uncover the truth. His investigation eventually reveals a heartbreaking secret: Saki has been working undercover as a bartender, using a fake identity and age to secretly fund his expensive cram school tuition. This discovery adds a layer of profound sacrifice to their sibling bond as he learns the true cost of his education.