The Pretty Side Character Is Useless? The Chaste Male Lead Insists on Kissing Her

[Transmigrate into a book + Cannon-fodder female side character + 1v1, both pure + Sweet and lighthearted romance + System + Supernatural school setting + Size difference] [F-rank, universally disliked, snarky, adorable succubus × S-rank, all bark and no bite, tsundere, cold-faced Demon King protector] Mo Wan'an transmigrates into a book as an F-rank succubus who dies after just three chapters. Hoping to get home by clinging to the male lead, Jiang Zhengyi, she overhears his System: [Warning: Host's mental power is 70% sealed. Find a target immediately and complete an intimacy task to break the seal.] Jiang Zhengyi: No need. I can handle it. [But you can't even open the door, and your legs have gone weak from the electric shock.] Jiang Zhengyi: Shut up! Mo Wan'an: Bro, stop pretending. This could actually get you killed! [Warning: Task progress 0%. Unable to open the door to the haunted realm.] To save her own life, she rushes forward and kisses Jiang Zhengyi. [Task complete: 100%! Seal broken: 35%! Kiss for five more seconds to break an additional 50%!] Jiang Zhengyi grips the tail curled around his wrist. “Who taught you that?” Mo Wan'an: “Being afraid of dying.” -- Later, everyone at the academy notices that Jiang Zhengyi has acquired a little shadow. “Take me with you, Senior...” “Let me have a bite. I'm really starving to death.” “...” Jiang Zhengyi gets fed up, so Mo Wan'an stops seeking him out. He panics and pins her in a corner, his fingers gripping her waist. “Why aren't you coming to me? Didn't you say you have to kiss me to stop being hungry?” Mo Wan'an: ??? Weren't you supposed to find me annoying? [Friendly reminder: Host has gone seven consecutive days without an intimate partner. Today's desire to kiss: 200%.] Jiang Zhengyi: “Shut up.”