Chitose Is in the Ramune Bottle, Vol. 3 (manga)

Kenta Yamazaki, former shut-in and otaku loser, has resolved to transform himself under the tutelage of Saku Chitose. He hangs out with Saku’s friends, practices his social skills, and even gets a total makeover. But Saku’s not the only popular kid in town, and his friendliness with Kenta has gotten on the nerves of his fellow normie, Atomu Uemura. When opinions clash, which popular kid will come out on top.