Pixiv artist "いぷしろ", known on e621 as Shiron_(artist) (to disambiguate from Shiron from Legendz) posts on FurAffinity under the name "Omikuro".
Some works crossposted on both sites. Very similar styles on works exclusive to either site.
I also made a query with the artist on FurAffinity to verify. (His reply is below my post. Broken reply-tree.)
http://www.pixiv.net/member.php?id=1689025
http://www.furaffinity.net/user/omikuro
There have been few instances of Omikuro as a tag, but most uploaders are aware of this being Shiron_(artist) and tag as such upon uploading. Other users and I have changed Omikuro uploads them as they came along to Shiron_(artist) to group them with the majority of his works already tagged as such.
Last time I heard, e621 favors the Romanized usernames of artists as chosen by the artists themselves (usually on FurAffinity, Tumblr, or Twitter) in lieu of names comprised of Japanese text (often Pixiv). Akin to Sasamix with his name "ささみ" on Pixiv, but "Sasamix" on Twitter and FurAffinity. (Granted, "ささみ" pretty much translates to that anyway.)
So I propose the following tag alias:
shiron_(artist) → omikuro
And maybe also
いぷしろ → omikuro
Unless "いぷしろ" is something rather general. Google Translate says it translates to "Ipushiro" (which is probably where "Shiron" comes from). [EDIT: actually, we got "Shiron" from one of the artist's previous display names on Pixiv, "しろん". "Ipushiro" seems to mean "Epsilon".]
But I often find that such translators are not a reliable reference. As usual, I would very much prefer someone more savvy than me with Japanese language and translating to make this judgement.
Updated by user 59725