The game's not available anymore it seems. They revamped the nekogames site and that page remains broken. I was hoping someone had an alternative.

No, it's still there, though a bit out-of-the-way:
http://nekogames.jp/g2.html?gid=PRM

For reference, all older games can be found by clicking "[PC] Nekogames" underneath the scrolling banner, which takes you to the old site.