The Host with a Little Boy and His Dangerous Neighbor(2019)

Komochi Host no Kiken na Rinjin

Seiya is a nightclub host who is secretly raising his late sister's little boy Tenma as his own. Cute and angelic, Tenma is the only love and comfort in Seiya's life. Late one night, a drunk man suddenly kisses Seiya in the elevator of his upscale apartment building, and the dangerous man turns out to live next door...!! A parenting love story about a suspiciously handsome author and a host who isn't interested in love!

(Source: Renta!)

Note: Includes one extra chapter.