麻雀中毒 (Mahjong Chuudoku)

Background
The song was first uploaded on June 22nd 2012; and withing two weeks have reached over 200,000 views. According to Owata-P's video description on the song, he wanted to make a "mahjong-themed" song. With the previous being "Antichlorobenzene", he also made a "how-to" on the making of Mahjong Addict.

It tells a story of Len and Rin playing mahjong; ambitious on trying to win and not to lose to Rin, he wanted to show who was the strongest. Though, in the end Rin was the one to say ron (in mahjong, a term you say when you win).