The Fear Nothing Kanji shirt, white can be randomly found in a locker during the “Pachinko Model” mission.
There is also a Fear Nothing English t-shirt.
Note: The Fear Nothing shirts are in specific lockers. As lockers are random, you don’t always get the lockers containing them. Running back out and in will reset the locker randomization, so you can keep exiting until you get them.
This shirt is in the bottom third-to-last locker on the left wall.
Thank you Burrick, Vomher and Rumikolol for the screenshots and details!