PSP title MonHun Nikki: Poka Poka Ailu Mura, the spin-off game feature the Monster Hunter cats, went on sale on August 26. It looks like it was really popular.
Japanese websites have been collecting photos that show that the game is sold out at a variety of retailers (Sofmap, Bic Camera, Yodabashi Camera). These kinds of things are anecdotal at best, so stay tuned for the official software sales.
The West often complains that there aren't enough PSP games. Meanwhile, Japan seems perfectly happy!
【都内全滅】『モンハン日記 ぽかぽかアイルー村』が品薄状態、入手困難に！！ [オレ的ゲーム速報＠刃]