What is the name of the instrumental that plays in the majority of the season 2 intro scenes when Midoriya is explaining the origin of heroes?
The song is called "Avant Title" in the second season original soundtrack! I was looking everywhere for it too. It's so beautiful, my heart is about to burst :D
You must be talking about Watashi ga kita
Find a youtube link to it here
Got you buddy. As you mentioned episode 3 of season 2. It is one of the variations of the All Might theme. Updated my answer. :-)