Blue Box is a Manga/Manhwa/Manhua in english language, Comedy series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Taiki Inomata is on the boys' badminton team at sports powerhouse Eimei Junior and Senior High. He's in love with basketball player Chinatsu Kano, the older girl he trains alongside every morning in the gym. One Spring day, their relationship takes a sharp turn ... And thus begins this brand-new series of love, sports and youth!