People speculated that this was in relation to a comment he made in a live about wanting a "fresh start". However Treow just tweeted this link
I'm too sleepy to do a full translation, but the gist is that he is very sorry for deleting things all of a sudden, that he feels bad for doing this to the people who have supported him and his songs all this time. However, he wanted to share a story. Apparently there were some comments on DYE (which was first uploaded in February of this year) about how the song was very similar to KAT-TUN's NEVER x OVER. So he went, looked up the song and found this:
EDIT: The YT has been now privatized, but have a link to a mashup of both songs here. KAT-TUN can be heard on the left speaker and Luka on the right.
He was, of course, incredibly shocked. He does not know about any of the details behind this, but he would like those familiar with DYE to give the song a listen and compare.
Here's a YT mirror of DYE, for reference.
ETA: To clarify, KAT-TUN's song was released on November 17th of this year, while DYE was released back on February 1st.
SON OF THE ETA: From treow's Twitter: Apparently the plagiarism issue has nothing to do with the mass deletion, since apparently he only found out after the fact. Sorry for the misunderstanding!
REVENGE OF THE SON OF THE ETA: More from treow's Twitter, regarding AV's future at Nico.
RETURN OF THE REVEN OF THE SON OF THE ETA: Kitajima Shizuka from ELECTROCUTICA asks people to please refrain from pointing fingers at innocent parties.
Even if all of his works have been deleted from Nicovideo, it is still possible to keep supporting AVTechNo and buy his music through both iTunes and Amazon.
- ← DYE | NEVER x OVER → DYE panned 70% to left, NEVER x OVER panned 70% to right with Audacity project view and other stuff, pw is souzou!
- NEVER x OVER instrumental with DYE vocals and viceversa. Also available on YT.