Soooo I was a little disappointed that they added this pun…and then DIDN’T EXPLAIN IT!
Shougo here says, “Shougo dakedo, dai-gosan!” A “gosan” is a miscalculation, and by adding “dai” in front of it, it makes it a HUGE miscalculation.
However, the pun is in the fact that the word “dai-gosan” sounds just like “daigo-san”, aka Daigo, the seiyuu and real-world personality Shougo’s character is based on.
So he’s literally saying, “My name is Shougo, but I’m a Daigo-san!”
HA. AND ALSO HA.