Source: https://kakuyomu.jp/works/16817139557675080183
Synopsis
The main character’s name is Natsume Sho. He was a boy who fell in love with his childhood friend’s older sister when he was little. At the time, he was a crybaby and weak, always hiding behind the girl he fell in love with for the first time……
That one girl was Nakajima Sawa. When she was little, she was strong, manly…..and cute.
In the meantime, Sho confessed his feelings to Sawa. However, Sawa, who’s older than Sho, brushed it off lightly.
[When you grow up, I’ll do any kind of naughty things with you !]
What……! He’d learn that those words were fatal to him…..
But more importantly, the romantic comedy season has begun !