Anpu is a cat who frequently loiters in front of the Saiki House. He was saved by Kusuo when he got trapped between two buildings and got attached to him despite Kusuo's continuous rejections.
Anpu shows up a couple of times and is also part of the “everyone else loves me so why doesn’t Saiki” brigade. After being saved by Kusuo, he starts to visit his house to make Kusuo pet him. He once got Kusuo (disguised as Sai) to aid him in trying to woo a female cat Pushi. Later on, Kusuo pets him after Anpu saved him from a chasing cockroach.
His name is a pun on Anpusi (Animal-Psi) the ability to psychically communicate with animals.