Hana Shinobu no Koi

A boy, who always gets bullied is told by his dad that the day he turns sixteen he is going to get someone that will always be with him. The boy, Kazu-kun, believes it will be a fiancee, since his dad got a wife (his mom) and his grandma a husband (his grandpa) on their sixteen birthday, but oh surprise, it is a boy and he is a ninja. So begins the story between Kazu-kun and Masanaru and their romance.