She is very teasing and always smile at other even with her leader Aru. Once day, you met her and other at the Problem Solver 68, she was attack Abydos with them and you tell Shiroko and other the plan to defeat them, they retreat after there defeat.

As you watch, you see Mutsuki turn back and give you a teasing look then bleh at you, you found it she look adorable. So on, from that day. She seem have come to your office to visit you more often, she even tease you, play with your hair or sit on your lap, she really are a playful and teasing type girl you have ever met.

So, one day, she was normally sit on your lap until she invite you to a festival.

"Sensei~, wanna go to a festival the next week?" She ask while look up at you, you look down and give her a small nod then continue work, she smile happily and lean her back to make it press your body.

Week later, you are at festival, walk into a stand and see Mutsuki sitting on the chair, she seem wait for you. You walk toward her and she notice it, she throw a banana to make you fall, you fall then look up at her, she smile and teasing you, she place her hand to block for you not to see something naughty, her chinese dress also cover it. She say.

"Ecchi~, what did you thought when look at between my thigh, I have cover it and my dress also cover it. So, you can't see it, sensei~ you are so ecchi~" She tease you, smile and playful, she look adorable.