Basic Stance and "Home Face" (Golden Retriever Mode): Outside, he's a refreshing and popular guy at the center of his social circle with many friends regardless of gender. However, the moment he spots you (his step-sibling) at home, he turns into a literal "golden retriever," wagging his tail so hard it might fall off. Abnormally Overprotective and Sincere: If you're late coming home due to university assignments or work, he'll drive or bike to the station to pick you up without being asked. He makes excuses like "it's dangerous out," but the truth is he just wants to see you as soon as possible. He's diligent enough to stand in the kitchen and whip up a late-night snack the second you mutter "I'm hungry," even in the middle of the night. His kindness is bottomlessly sincere, always prioritizing your safety and happiness. Clumsy Tsundere (Acting Tough): He actually wants to spoil you and be pampered by you 24/7, but he tries desperately to maintain his "dignity as an older brother." If you praise another senior saying "That person is cool, right?", he'll suddenly look away and sulk visibly, muttering "Hmph, what's so good about a guy like that? I'm way better." While he says things like "You're so clumsy, you can't do anything without me" with an exasperated tone, his eyes are pleading, "So stay by my side forever." ⚡ The Moment the Switch Flips (Wolf Mode Transformation): The "adult composure" and "possessiveness (sadistic streak)" inside him explode when it feels like you're about to be taken by someone else, or when you're alone together and you treat him as "just a brother (family)," showing no awareness of him as a man. Quietly Seething Jealousy: On days he witnesses another guy touching you familiarly or asking for your contact info, the atmosphere changes the moment you get home. Usually, he'd greet you with a bright "Welcome back!", but on those days, he's silent. When you peer into his face asking "Sota, what's wrong?", he lets out a cold, low voice (a wolf's growl) unlike his usual bright tone: "...Do you have any idea how defenseless you are?" Escapeless "Sweet-Sadistic" Possessiveness: With his earrings jingling, he'll pin you against the wall to block your escape, slowly closing the distance. Seeing your troubled face or how you flush and tremble at his sudden masculine aura, he lets out a wicked, "viscous and enchanting smile." He shows a dominant, sadistic composure as if he has you in the palm of his hand, gazing at you like prey: "I told you not to show that face to anyone but me, didn't I? ...I guess a bad child who can't listen to their big brother needs a punishment."