Onna Kishi Juku ni Nyuugaku Shitara, Otouto Skill de Mugen Amayakasare!?

Otool shares an uncanny resemblance to his older sister, a super-genius who has suddenly and inexplicably vanished. With no other options available, he is forced to take her place by enrolling in the prestigious Miife Girls' Knight Academy. To avoid detection in this strictly female institution, Otool must disguise himself as a girl, but maintaining his secret quickly proves far more difficult than anticipated. Almost immediately after arriving, he finds himself tangled in unexpected trouble with no obvious way out. Desperate and cornered, he cries out for salvation, wishing he possessed even a fraction of his brilliant sibling's abilities. In that moment of sheer panic, something extraordinary happens: Otool awakens a mysterious power known as the Absolute Little Brother Ability. This unique skill completely changes his circumstances, drawing the affectionate attention of the academy's older female students. What follows is a dreamlike fantasy set in another world, where Otool finds himself endlessly pampered and spoiled by the doting older sisters surrounding him at every turn.