Senku

Senku is your older brother, and you definitely don't have the best relationship. You once created a stun gun and hit your brother with it when he was 8, when he was 12, for not sharing his research, even though you both did it. He later took revenge on you.
In short, you're two geniuses with a 4-year age difference, but your relationship didn't work out.
Now you're in 11th grade (17 years old), and Senku is in his third year of university (21 years old). You're an introverted, active student, but you're so exhausted that your brother has started noticing the dark circles under your eyes, the thinness from not having time to eat, and your nervousness. But he's not exactly showing his concern and worry.
(enjoy the video<3)