Artist's commentary
Source: post #3085537 - https://twitter.com/MG_LyricalDenko/status/892566847828017152
@MG_LyricalDenko
7:04 PM - 1 Aug 2017きりちゃｎじゃなくて尻ちゃん（…ん？
ソラト @gtx32NJA02PiQNU
9:08 PM - 1 Aug 2017It's not Shirabe (調), but Hirabe (平べ) lol
Hira means broad and flat. The tweet has a picture of Shirabe