“And if they’re from a time before that happened?! What then, huh?!”

Shinjiro being alive for his friends, that’s a blessing! Sure, Gokudera doesn’t know him very well, and he’s not a very good example as far as friends are concerned, but having seen and felt the loss of a friend, he understands that keeping away would be painful to those that may have experience losing Shinjiro.

“I refuse.” He responds, stubborn about this.