Ojou to Banken-kun

Ojou to Banken-kun manga summary: Senagaki Isaku will be a first year high school student starting in spring. Her grandfather is the third head of the Senagaki group, a yakuza organization, so she is feared by those around her. However, starting from spring, she hopes to make normal friends and normally fall in love. She is admitted into a high school further from her hometown, however, the overprotective young head of the Senagaki group, Utou Keiya, (26 years old) falsifies his age and enters the school with her through a backdoor admission...?! Keiya proclaims that love is too early for her although Isaku is perfectly ready. In truth, she has held an unrequited love for Keiya for quite some time.