IDK if Tatsh officially confirmed that Sacred Ruin is by him,but I'd say it's a Tatsh song judging from the song name and the overall style of the song.
Lokamp wrote:Meanwhile in Namco
Taiko 3DS 2's website got updated again, with two new Variety songs (Kumamoto Surprise and another collab song whose mascot can be selected as team member for the Story mode) and that fabled Sacred Ruin (セイクリッド ルイン) song that was mentioned by Zeami/Tatsh to be the 1st Tatsh song on Taiko, if I don't recall wrong
Updating TT soon
(though I have to admit my Tasshu senses aren't always accurate,back then I thought he made Ao no Senritsu for one)