Toraji-senpai no Shiikugakari

It's the first day of her long-awaited high school life ♪ In all her excitement, Ruki ends up running late. As she rushes to the entrance ceremony, she hears a voice coming from inside the gym storage room! There, she finds a ferocious beast, or, rather, a handsome man!! The person in the storage room is second-year Toraji-senpai. He even told her, "Ruki is my zookeeper!" But Ruki is constantly at the mercy of this elusive senpai who is sometimes mean and sometimes kind...!? Can she tame this free-spirited handsome man?! A thrilling love story ♪

(Source: Kodansha, translated)