You can tell Asaki's having fun singing the song; at the end, after one last shout of "O-KOOOOOO-MEEEEEEEEE!", he delivers the following spoken line:
"Ahaha...okome oishii!" (Rice is delicious!)
The fact that Asaki and 96 don't appear in the event, presumably due to being Reclusive Artists; instead, they have two stand-ins pose for them. Asaki's in particular is a Caucasian male who looks nothing like him.
Within the same event, MAX MAXIMIZER appearing in a black hooded robe and darkly introducing himself as "the last guardian of corruption and despair"...followed by his collaboration partner DJ TOTTO telling him "Don't worry, I'm a transfer student too."
"FLOWER" being crossed over into nearly every active BEMANI series, even Miraidagakki FutureTomTom, and even going as far as to be arranged one-to-one just so it could be put into GITADORA.
The Tenkaichi otoge sai Zenkoku issei nintei taikai event is a Crossover event between multiple companies' rhythm games—specifically, jubeat saucer fulfill, maimai ORANGE, Taiko No Tatsujin Kimidori Ver., and GROOVE COASTER EX. Guess which song gets crossed over to the non-BEMANI games? "FLOWER".
Any time wac makes a public appearance, he always wears a silly black cat mask.
"STELLAR WIND" seems designed to troll players with its ever-so-subtle changes:
The song is natively 160 BPM, but in IIDX, it's 2 BPM faster and has an extra measure for no reason.
In jubeat, its Extreme chart is exactly the same as the Advanced chart, with one less note and turned 90 degrees.
In REFLEC BEAT, its Special chart not only has the same number of notes as the Hard chart, but it's rated one difficulty level lower.
The "Try To Sing" series of With Lyrics songs follow the artist format of "<original artist> rejected by <singer>". The Try To Sing version of "Nigra Ludia" in particular is credited to "Akhuta rejected by Akhuta".