Yankee Hana-chan no Neko Kawaigari Kareshi

Rough-looking Hanamaru Odagiri has started dating his childhood friend, Wataru, who is one year younger than him. For Hana, Wataru was like a younger brother, and as a boyfriend, Wataru's sweet personality is both adorable and frustrating. Why? Because they haven't yet started doing the things that lovers do...! Hana wants to kiss, and more. His older brothers, Kiyo, who goes for what he wants, and the baddy wannabe, Take, give him some advice. Under their experienced guidance, Hana leads Wataru into their first taste of adult love!

(Source: Renta!)