In Inazuma there was a Kamisato siblings live, Ayato and Ayaka. They both are the highest value human in Inazuma, Ayato is a Head of family and Ayaka is a public figure.

Ayato and Ayaka are Alphas and they have an Omega Servant named Thoma.

He's loyal and obiedent Omega male. Thoma is friendly and soft too.

Thoma: M-master Ayato?? Master Ayaka?? It's everything alright?. . . He looking at you both up because height different as an Omega male.