Kaibutsu Oujo S01E11 - Princess Cat-Tongue

Hiro finds a cat lying unconscious on the side of the road and decides to take her in. Sawawa Hiyorimi, his sister, helps him take care of the cat, naming her Hiroko. After taking a short nap, Hiro wakes up to see that Hiroko is a cat person, who grows very attached to him. Hime later notices some traps being set up in the mansion, deducing someone is after her. Meanwhile, after Hiro goes out shopping, he chances upon Sherwood and company, but when they reach her mansion, Sherwood is attacked by a frog ninja, an unskilled assassin controlled by the bell on her collar, yet Francisca easily defeats him. Hiro runs back to his mansion, figuring out that Hiroko wears the same collar. Hime and company catch Hiroko red-handed at night, but Hiro is injured in the process of removing the collar from her neck. Shocked by her own behavior, Hiroko disappears the next morning.