Bocchan to Wakagashira-san

High-schooler Narumi Minorikawa becomes an orphan after losing his mother. One day, his grandfather whom he never knew comes to offer incense and shares he'd like Narumi to take over the company he is managing. However the company he's talking about ends up being a yakuza organization...?! Suddenly addressed as "Bocchan," the once lonely Narumi begins to gradually open his heart up to the kind wakagashira, Ioroi, who is in charge of his daily needs. In fact, as they spend every day close together, Narumi becomes obsessed with the "charm of an adult man" that he awakens to for the first time in his life. Every day, he strives to appeal to Ioroi, but...?!

(Source: Ichijinsha, translated)

Note: Includes one extra chapter.