Mon on saya help.

[Shuko]

Hi

Could anyone help me identify which clan used the two swans facing each other mon. 

This is on both sides of a black lacquered saya from an aikuchi tanto.

thx

[moriarty]

対い鶴- Two Cranes

旗本石河氏- Ishikawa Clan (Hatamoto?)

[SteveM]

And others

使用苗字　　　飛内、竹屋、広橋、森、石河、宮重、中西、望月、森岡

 

Always important to remember many families used the same crest. There isn't a one-to-one relation to a crest to any one family, excepting the imperial family.

[AdamH]

I believe it originated from the single crane crest from the Hino family (Kamakura). 

The specific mon you have was used by these 4 families. 

Ishiko, Ishimaki, Nakanishi & Miyashige