>>13005485>TenmaYour comment reminds me of this footnote in the Genki textbook. I have also seen senpai being romanized as sempai a few occasions for this reason, so maybe that is why his name is spelled this way.
>>13006925From the wiki, their collab name is called "明日花" which means "(明日) tomorrow (花) flower"
"明日" can be pronounced as ashita or asu (or even myonichi)
"花" can be pronounced as hana or ka
I would instinctively read the name as ashita hana but all of them could be valid