
I'm planning to read this one due to the psychological aspect and vibe alone, but can someone tell me how present the bl/mlm theme is ? and how prominent?

Barely. There are tons of metaphors that hint to it being a queer coming of age story, and the main characters like each other in a non-platonic way but seeing as an anime will be made of this, I doubt it’ll become any more bl than it is right now which is, again: barely.
Right now the story is more focused on them staying together (and figuring out the overarching plot) rather than being in love.
this is amazing...