Dear Tenant (2020)

For the past five years, Lin has been looking after the son, Yo Yu, and the elderly mother, Mrs. Chou, of his deceased boyfriend, Li Wei. They live together like a family, and it is Lin's way of remembering Li Wei - by continuing to be in the life he once had and loving the people he once loved. But when Mrs. Chou passes away, her other son, Li Gang, returns from overseas and discovers that Mrs. Chou's property is passed on to Yo Yu, who has been legally adopted by Lin. Li Gang contacts the police, accusing Lin of killing his mother. As the ensuing investigation continues, more and more evidence mounts against Lin.

(Source: IMDb)