His and Haru's name both have the character for spring (春)
Haru is seen with red slitted eyes in the Ginsenkei video
The straps on his clothes are similar to those on Ryuu's
Shunran's wife is Saha
Shunran is related to Mikichi
Both have similar cheek coverings
Shunran may have been in a relationship with both Saha and Tatsumaki, having been shown in pictures of his closeness to them both. As a result, Haru and Ryuu may have had seperate mothers, making them half brothers.