This is Shun, who has reverted to her childhood body after taking Saya's medicine! Not only her body, but also her spirit seems to have been pulled along by her young body, and she tends to act according to her instincts.Normally quite calm, Shun's new youth has given her youthful vigor, resulting in a peppier, more energetic personality. She's also quite childish, wanting to play more, specifically with Sensei. This clashes with her knowledge of Shanhaijing and her general intelligence.