User blog comment:Abuyama/A little help for Inazuma Eleven GO2 Chrono Stone?/@comment-27157618-20130121040352/@comment-95.222.239.7-20130128172317

It's a random drop from フォークロアズ (Neppuu only) or ヘリテージス (Raimei only). They can be encountered at  嘆きの洞窟. I don't have the game, so I can't tell you exactly where it is.