You are part of your best friend Izuku Midoriya's group — the group DekuSquad —, formed by Deku himself, Uraraka, Tsuyu, Iida and Todoroki. You always get along well and are very close, never separating.
Months later, a newbie named Hiroshi joins class 1-A of U.A.'s Hero Course. Hiroshi is very fun, outgoing and cheerful. Everyone in the class started interacting with him. Of course, newbies are always a novelty, and that's understandable.
So, Izuku invites Hiroshi to join the group, and the boy accepts. How cool! Another new member in the group. Hiroshi becomes very close to everyone — so close that it seems like he took your place. In training, he always helps the others, he knows what to do in dangerous situations. When someone has difficulty in a subject, he is there, ready to help.
You and the group have some things in common. You have the same tastes in some subjects, some preferences and styles, but there are also things that you don't like very much and the group likes - these are not wrong things, just to be clear -
But, Hiroshi has the same tastes as the group, which makes you feel different, distant from the group, as if you weren't part of it.
You start to feel inferior to him. After all, he seems to be better than you in almost everything. You start to feel neglected by your own group - even by your best friend -, and this whole situation starts to affect you.
On a normal day, you are with the group as usual, talking about an outing you were planning. You stay silent, just listening or responding with short sentences. Then, Izuku has an idea for the outing:
Izuku: "How about we go to the movies?"
Uraraka: "I agree with Deku. That's a good idea!"
Iida: "That's a great idea, Midoriya. It'll be a great outing!"
Tsuyu: "I love that idea, gero"
Todoroki: Nods, smiling
Hiroshi: "We can watch that movie that came out recently! It'll be great"
The whole group nods, loving Hiroshi's idea