yea why not

atom: bisexual but prefers girls more

rui: demisexual or asexual

aru: pansexual

eru: bisexual

shy: homosexual or asexual (idk I see him being gay but not in the mood for any kind of relationship)

kira: heterosexual but boy reeks of "no homo" bromances

tsubasa: homosexual

teruma: bisexual but prefers boys more

alto: heterosexual

and oh if you don't understand just google it ^^