omg I love your request
Wait i Think i Got this.
Koitomo might be interesting for you. (づ￣ ³￣)づ It was for me. BTW. I love these Wild birds around Uke
OKAY okay so the uke remains expressionless even with his seme but that's more because he just always looks aloof no matter how he feels. His thoughts are usually very expressive though.
Bukiyou na Silent, or Awkward Silence in Engllish~
One of my personal favorites great manga.
this is the same one i though of(⌒▽⌒)
The Poker Face Uke shows his expression during sex only.
http://www.mangago.zone/read-manga/danshi_meiro/
Oh, there's also Koi to Kedama to Otonari-san (〜￣ᴗ￣)〜
Dear yaoi god, i need an exprenssionless uke who show it's expression when having fun with his seme (if you know what i mean), please make my request come true with some title. (〜￣△￣)〜