so, i will explain a little bit about Tomoe
Background Character:Tomoe, she is basicly half human and half demon,before she got demon power, she is Onna bugeisha (warrior girl) her position on battlefield was a General. she got the power after she betrayed by her allies in the middle of war situation, and burn alive in Susano Temple, before she died she made a contract with the ancient demon, inside the temple. the name of the demon is Keyaku Oni.

Tomoe Power: she can borrow the power from God and Demon, more sacrifice she use for the contract, more powerfull she will become, the sacrificial terms can be human/blood,glory,wealth,gospel etc.

Tomoe Role: she can be summon by anyone who needs her help, she can do anything summoner wants as long as they can obey the contract.