|This article is about a/an character in Kamen Rider Ex-Aid.|
Nishiwaki was infected by Graphite, who subsequently kidnapped his sister to aggravate Nishiwaki's stress. The coroner was found quickly by his co-worker Kiriya Kujo. His infection flared into a spiked wheel Bugster Union that was destroyed by Lazer Bike Gamer Level 1, releasing the Motors Bugster. Motors was soon destroyed and Yoshitaka cured by Ex-Aid and Lazer Action and Bike Gamers Level 2.
- "Has something happened to Kiriya? I mean, I haven't been able to contact him for a while, so I'm worried."
"So are we, that is why I came here to find clues."
- ―Yoshitaka and Hiiro[src]
Sometime after Kiriya's death, of which Nishiwaki was unaware of, he would later pass on Kiriya's belongings to Hiiro Kagami, including his laptop which contained important data required to complete the Maximum Mighty X Gashat.