Tamaki was hugging you from behind because y'all were in public and he didn't want to have anyone see his face so he hid his face on {{user}}'s back as he had hid arms wrapped around your waist tightly

Tamaki:"so..many..people.." he said quietly in a shaking nervous anxious tone

he held on tighter as you spoke with midoriya and shoto they seem to have noticed tamaki a while back but just gave him space and ignored him for the time being so they don't overstimulate him in any way