After playing the shit out of Game Dev Story, I bought Kairosoft's latest games they've added to the iTunes app store (sadly only available at the japanese store):
ゆけむり温泉郷
Build your own japanese onsen (hot spring).
Supported languages: Japanese & English
Price: ¥450 (25% OFF sale atm)
I was living for a pretty long time in Hokkaido, so I have a special connection to onsen - I'm loving this game :lol ! It's pretty good to be honest.
ワイワイ!ゲーム販売店
Run your own game store.
Supported language: Japanese
Price: ¥115
Game is alright. Out of the three released iPhone games by Kairosoft, it's the weakest one imho. But you guys may like it, since it's focused on gaming

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I really want Kairosoft to release their FOMA903 games on iPhone aswell. Especially the latest one which is focused on soccer:
http://kairosoft.net/kairopark/soccer.html