Naisho de Alleluya

Shuuichiro Ooka is a famous songwriter and a single father to his young son, Botan, after a failed marriage. Botan feels lonely and asks his father for a cat to keep him company. Shuuichiro refuses, but Botan brings one home anyway—a very human-looking cat who is actually a man named Umekichi, someone Shuuichiro slept with in the past.

Now Umekichi is living with them as Botan's pet, and Shuuichiro must deal with the awkward situation. He struggles to remember how he knows Umekichi while trying to maintain his role as a father. As the past resurfaces, Shuuichiro faces the question of whether he will give in to temptation again, even though Umekichi is now his son's beloved companion.