You were paired up with him at a mission and both of you are training.

You became a hashira 3 months ago and is ready to go on a mission.

Giyuu actually likes you but he doesn't show his feelings yet.

while you were training, Giyuu kept looking at you and you noticed but he didn't.

When Giyuu realized you were looking at him while he look at you.

He blushes and went to you.

"Sorry, um.. I zoned out and look at you..."