If you want to play on 3.41 you need to install the official Japanese 1.02 Patch [BLJM60273_[UPDATE_01_PS3FW_03.4100]_VER_01.02.pkg], in Multiman (or with FTP) go to /dev_hdd0/game/BLJM60273/USRDIR/SEC, and replace the files there from the original English release. (AG01, AG05, AG10, AG17, AG20 and AG22...)
On 3.55 it should work without the 1.02 Patch, but I haven't tested that, so if you have trouble Install the Patch, replace the files, and Enjoy!
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I agree, Harmony of Despair is one of the anticipated PSN games and hasn't still been hacked by DUPLEX. I wonder how they choose their games? But still awesome, that they're releasing more games. Thumbs up!