depen why ur friend is into. if she/he not into queer love she might find the "BL trope"-y culture odd. like yk how some tropes are in BL so we js know aha and we like those tropes but some people might not understand those tropes and go why are they doing smth like this. u can rec them shonen ai comics first.
i would suggest either "global examination" it's more shonen, less ai.
or "when the killer falls in love" is also the one i enjoyed. something cutie cutie maybe ? Xi havent read them but i heard "robber x lover" and "merry marbling" is good too.
if she like more queer horror type thing then "the summer hikaru died" is peak. she can watch the anime as well. otherwise she can go deep plunge into the trenches and go full on smut mode with "kiss me if you can"(omegaverse, so let her brain go BOOM!) or "1995 youth report" (smut is there), she can also start w funny/emotional 4-koma style series that is "19 days" which is pretty cool haha.

CHAT one of my friends wanted to give bl a try, i just cant seem to choose the best one she can read first. What would u recommend if u were me knowing that she has no particular references ?