Kumihou said: I'm thinking the same thing, but the ears, doesn't Reisen 2 have more earth-rabbit like ears? Unless the Pixiv tags state something different.
I'd agree with you, but the pixiv tags say 鈴仙 which is how Reisen Udongein Inaba's name is written... I suppose this is regular old Reisen, and we can chalk it up to artistic expression.
Tags aren't standardized enough on pixiv to make a judgment based on that alone.
The artist's other work involving Udonge are tagged both 鈴仙 (Reisen) and うどんげ (Udonge) while this submission and pixiv #32788555 have only 鈴仙.
On the other hand, there's no visual distinction between this work and post #1320941 which is clearly tagged うどんげ. This suggests that the artist's tagging is inconsistent and that this submission depicts Udonge.