Theory: Ryu's domain is straight hands, no CT, no nothing
Basically, his handsign looks like he is about to crack his knuckles right? Almost like he is about to start throwing hands
And i imagine it will look like the garden of an old Japanese castle, all luxurious but wide enough to accommodate a fight. Like the outside of a dojo, maybe at night with fireworks to make it even more dramatic
Also, makes sense thematically, the guy interested in having a satisfactory fight doesn't need a lethal domain, i would go as far as arguing his CT goes against his philosophy
Think about this, you want to brawl and your CT allows you to snipe people, you would be bored af regardless of how poweful you are relatively
Yes you could live comfortably (this would explain why he said he had everything in life, his CT allowed him to rank up in the social system, probably as a general or simply as someone with a technique so powerful he only needs to fire it once or twice in the battlefield and then get paid)
He probably lived as a samurai too, so he truly won in life (considering the status and stuff)
But does that matter? Of course not, Ryu of all people sounds like the kind of guy to craft a domain with the sole purpose of fulfilling his dream. Of course he didn't get to use it, but my point still stands