This feels more like a coming of age romance than strictly BL no? I like how their types are vaguely like each other. Also it’s so cute the mitsuru fantasizes about saving someone and falling in love while jiro fantasizes about being saved. Compatible from the start. It is difficult to date your only queer/gay friend because the fear of things going awry and losing that relationship comes with losing your only queer/gay friend too. It do be like that sometimes.
Also re: dating apps, I think minors should never engage with them. If an app explicitly wants to ascertain that you’re above 18 then respect that. If an app says it’s safe for kids to use, trust that it will be full of pedo predators because they never respect minor only spaces. Keep safe people.