Lying to Mom (2018)

Koichi is a son in the Suzuki family. He is a shut in who never leaves his house. He dies suddenly. The rest of the Suzuki family, father Yukio, mother Yuko and daughter Fumi fall into a state of confusion. Yuko, the mother, is so shocked by her son's death, that she loses her memory. Fumi lies to her mother and tells her "Koichi stopped being a shut in and is now working in Argentina."