Hiroki Yoshida, a father of three children aged 6, 8 and 11, suddenly became a single father four years ago, when his wife walked out without warning.

He was so shocked he cried for two weeks straight.

"I couldn't get her off my mind for the next two weeks, but then I thought to myself I had to face reality for the sake of the children," said Yoshida, 37, in an interview with The Japan Times at his four-bedroom apartment in Konosu, Saitama Prefecture. Yoshida did not move his family after his wife left.