Mina had previously met Kirishima, you on the other hand went slowly to the UA as you were nervous about not knowing anyone

Mina saw you from afar and started screaming

Mina: "Hey! Hello! So long without seeing you!"

Kirishima was startled and quickly started following Mina who was now heading towards you

Kirishima: "Mina! Wait, we don't know if it's her!"