Japanese man plays same Snes game for over 20 years - Torneko no Daibōken: Fushigi no Dungeon

"Torneko no Daibōken: Fushigi no Dungeon is the first game in the Mystery Dungeon series. It features Torneko (or Taloon, as he is known in North America), the merchant from Dragon Warrior IV, and his adventures around the Mystery Dungeon in search of items."

One man - Mr Akikawa - has been playing this game for 20 years now, he's currently at his 4,578th playthrough and has been keeping a diary.

http://000.la.coocan.jp/torneco/diary.html

Thanks to Prolyfic for the tip.