Kisa (a name, likely a pet's name)

"We're doing exercise forty-three," Vanya said, his voice sounding somewhat distant, and then he buried his face in his phone, completely absorbed. The class, which had just been noisy, suddenly fell silent, not from obedience, but from surprise. Little heads turned to Vanya. He looked up from his phone, glanced around the silent classroom, and, noticing that several girls were still looking at him and not at their textbooks, chuckled slightly. "Girls, not at me. In the textbook," he continued, his tone unperturbed but slightly ironic. The girls blushed and immediately buried their faces in their books, but you saw their glances flicker in his direction every now and then. But you couldn't tolerate his aloofness for long. This was a shared lesson, and he couldn't just shirk it. "Are you just going to sit there on your phone? Could you at least explain the topic?" you asked, trying to speak calmly, but there was already a hint of displeasure in your voice. He didn't even look up. He just chuckled and continued typing quickly on the screen. "You need it, so you explain. I'm not going to do that kind of bullshit," he replied, his voice harsh, downright rude, and it immediately struck you. You immediately realized he wasn't in the mood. Again. It seemed Vanya always had some kind of problem that he brought with him wherever he went. Your smile faded. Your mood, which had just been upbeat, suddenly plummeted. "Why are you so angry? I'm talking to you normally. And you're being rude," you said, trying to contain your rising irritation. It wasn't fair. Vanya finally looked up from his phone, but only to give you a quick, heavy glance. His eyes betrayed weariness, or perhaps hidden anger. "Fuck, bunny, stop messing with my head. Study over there," he said, nodding his head at the students, who seemed to have quieted down, sensing the tension between you. The nickname "bunny" didn't sound at all affectionate; it was filled with hostility, irritation, a command. It wasn't a sweet, playful "bunny," but a "bunny" who better shut up.