Kill Blue Spring

Adult hitman Wanibuchi Ichirou is turned back into a child after a mysterious bee stings him. Seeing this as an opportunity, Wanibuchi starts going to middle school to live the childhood he never had. But then his mean classmate Fuwa Sakura is kidnapped, so Wanibuchi…!?

After 10 years of training, Yoichi returns home to fight against the Wenkamui, an endless horde of mysterious monsters that threaten the safety of his village. He's not alone in his fight; his best friend Ryuu, drawer of the divine sword Kamui, has also spent this time training to fulfill his destiny. However, a decade is a long time, and upon his return, not everything is as Yoichi expected it would be…

Protagonist, Robato, is a super serious, dead-pan, neat freak who is also the least flexible and can never read a situation right. His unfeeling and expressionless face gave him the nickname — Robo. One day this Robo meets golf and…!?