Ottoman cape and vest, 1890s. Whitaker Auctions.

Vol. 19, page 140 / Chapter 167, page 15

Vol. 28, page 158 / Chapter 249, page 8

Vol. 32, page 71 / Chapter 281, page 5

Vol. 33, page 176 / Chapter 295, page 4

Vol. 33, page 187 / Chapter 295, pg 15

Vol. 34, page 189 / Chapter 305, page 1

Vol. 36, page 53 / Chapter 318, page 6

• He seems to have normal ears, a stubby/rounder nose, and his face is a little broader and more chiseled- not nearly as pointy as his son's.
• He and Hiruma have very similar hair texture, so Hiruma might have gotten his spikey hair and hairstyle preference from his dad. The only difference is Hiruma's is longer (and bleached, obviously), and Yuya keeps his short.
• Both have those spikey sideburns.
• We never see his eyes. This is to help keep distance between him and the audience, but i can't help but wonder if he might have the same kind of sharp, angular eyes as Hiruma.
• We also never see him speak or open his mouth, so we can't be sure if Hiruma inherited his teeth from his father or not.

• Yuya might be graying on the sides, bc in this panel, his hair isn't shaded in with black on the far side.
• Despite facing away and being in the stands, Yuya is still extremely recognizable to Hiruma, implying he hasn't changed his appearance much.
• He seems to prefer traditional Japanese clothing as his everyday casual wear. And we know he was a shogi player.

• If i had to guess, Hiruma might have grown up in a very traditionally Japanese household environment. That might have been why he pivoted so hard into American Football and western culture, because it was so opposite of what he grew up with.
• Yuya mentions how he and Hiruma used to be very similar - that is, only believing in statistics and numbers. This could imply that Hiruma inherited his sharp intellect from his father.
• Yuya used to have a more aggressive play style, similar to Hiruma. But too many losses mellowed him out. Hiruma seems to play so aggressively in direct opposition to this decision. He refuses to become like his father.
• From what we can tell, Yuya is a pretty passive person. Hiruma says he's the type to go "I tried" and leave it at that. I wonder if this applied to his parenting of Hiruma too - if he would offer a lackluster praise of "You tried," instead of pushing or challenge his son further. This could explain why Hiruma seemed so frustrated by his father's decisions, and why he thrives so much on being challenged and taking big risks.
• This could also be why Hiruma pushes everyone around him to be their very best too (teammate and opponent alike - Kid comes to mind), because he's doing what he feels his father should have been doing in the first place. He's refusing to let the people around him down like his father let him down.