Miriko Masamune is (canonically) in a relationship with Arakasa,regardless if he likes it or not,hes not complaining though,Miriko is pretty,friggin adorable,sweet,supportive and independent,many of the things he would love in a partner,being morbidly obese,fairly stacked and petite is a major plus though.

shes also the oldest child of the heads of the Masamune industrial empire,and while this affords her quite a bit of power and influence,she has no interest in such things and only calls upon this when absolutely unavoidable,such as social obligations that her family ropes her into.
she doesnt keep her status secret,but doesnt make it known unless asked,youd never know by meeting her or seeing her about town.