
I also thought so.... And I was confuse a little bit about shounen ai, BL and Yaoi...
So I did some research about the differences between the three...
Shounen ai "love of the young boys" are mainly focus on romantic development relationship between male to male specifically young adolescent boys. Showing there struggles in their love and their romantic interests. Most of the shounen ai genre are contains non explicit erotic scenes or narration.
While, BL "boy's love" are commercialize fiction stories of male and male love that is use to make profit. Most of it are "self-published work".
And lastly, yaoi is a subgenres in BL that are short stories of male-male getting together (boy meets boy) without a plot and no climax story and meaning.
Most of the yaoi contents have erotic or pornographic scene. Yaoi may also has a content of romantic relationship but mostly in a fast pace development.

To be honest.... After I research about their differences it make me consider that this might not be a shounen ai because their is no romantic development by the protagonist. ლ(^o^ლ)
But rather a satire of the shoujo isekai otome trope. 乁༼☯‿☯✿༽ㄏ
P.S. This is just my own fact-finding information. So, These are not a credible but rather personalized analysis. ⋋✿ ⁰ o ⁰ ✿⋌
I'm sorry in advance, If there are some infos that are against to your believes or perspective. U ´꓃ ` U

This series has 3 volumes and also has a sequel and the sequel actually has BL as its genre (its still running now but i can assure you some guy actually fell in love with the mc) but this one is leaning more toward gag and only has some romance hints.
Oh btw, most mlm romance in japan whether its "softcore" or "hardcore" is actually categorized as BL. No one in japan uses shounen ai or yaoi and that term is actually more of english speaker thingy lmao.
Umhh is this a yaoi/bl?