The Landlord is in Puberty (2016)

Maeda has just moved into his new apartment to live by himself. While unpacking, a cute middle school student named Chie Satonaka suddenly appears in his room. She introduces herself as his new landlord, which pleasantly surprises him as he has never seen a landlord so young. His excitement is boosted further when the gorgeous Reiko Shirai, who lives directly next to him, also introduces herself as his new neighbor.