Go with Kurumu, questioning himself.

Tsukane brought Kurumu to the infirmary, depressed as he wondered why he had said such a thing to Moka. Kurumu meanwhile was in serious danger of spraining her shoulder with how much she was patting herself on the back from making Moka cry.

She turned to the saddened Tsukane as she thought to herself, 'Now to make him my ****...' To Tsukane's surprise, Kurumu proceeded to pull him into an embrace... In a manner of speaking, given his face was in her generous boobs. "You're sad, aren't you Tsukane?" she crooned. "Don't worry, Kurumu will make it better..."

...

"What am I to Tsukane?" Moka was also questioning herself. "Do I really just want his blood? Is that what he actually thinks?"

"How naive can you get?" the same voice from earlier spoke up. "Can't you see Tsukane is being manipulated?"

"What the? That voice? Who are you?" Moka asked frantically.

"I'm your inner self, using this seal as a medium to speak with you," the voice told Moka. "What that Succubus is doing to Tsukane is called a Charm, a spell that allows the user to control the opposite sex. And that's not the worst of what a Succubus can do... They can make a man their love **** forever with a kiss. You have to hurry if you want to save Tsukane from that fate, if he hasn't suffered it already!"

Moka went rigid as she processed that, before dashing off. She had to get to Tsukane, immediately!

...

Kurumu was now on top of Tsukane, smiling seductively at him, using her Charm to keep him docile. 'What's going on? Why do I feel this way every time I look at Kurumu?' Tsukane thought, trying to resist whatever this was.

Kurumu smirked, and leaned forward, about to kiss Tsukane. 'With this, my victory over Moka will be complete, and I get a nice little boy toy in the bargain,' she thought as her lips drew closer.