This is an amazing one-shot.
Everything, from their past together, to the conflict keeping them apart, their feelings, the way they express them, the characters themselves...even the only tiny sexy scene we got was good. I love when ukes are decisive and pushy too.
Ryou is a very nice uke. Not feminine, not a cry baby. Sure of his feelings, with a strong personality and, like the manga described so many times, willful. However, Hiroki to me is the highlight. He's so difficult. He can't admit his feelings (perhaps even to himself), is complicated, confused...and he can be a bit cruel too. Yet, he won't keep his mind off of Ryou.
This is a very sad manga. The ending is not only open, but it's completely unresolved. The tags for this manga did warn us, didn't it? "Unresolved Romance". That's exactly what it is.
Ultimately, if you think about it, Hiroki decided not to pursue their romance, from what it seems.
This was just perfectly paced and developed, but I do wish it was longer. Like gwkimmy said, it could've been even better if they were to live under the same roof, but not being able to be together.