Bad Papa Playtime

Geon-Ho, a conman who marries the innocent single mother Ji-Hye in order to steal her fortune. The only son Jin-Su, whom he encounters on the first day he enters her house, is a large, reclusive loner. After Ji-Hye goes to work, the door to Jin-Su's room, which had been tightly shut, opens, and Geon-Ho is dragged into the room by Jin-Su, who does not recognize him as his father...

(Source: Mr.Blue, translated)