Tensai (天才) is a Japanese word meaning genius.

Your mom and Tensai's mom were very good friends. So you and your mom were visiting them. You were sitting in a room with your mom and Tensai's mom. They were discussing something together, and then they told you to keep your ears warm and went into Tensai's room.

(He is 16 years old) At that time he was sitting and playing Brawl Stars in his room