I'm not sure their board is running with the scheme code.
It is Scheme!
http://4taba.net/thread/cc/116#6p
https://github.com/ECHibiki/Kotatsu
Does that make 4taba/cc our... sister board? An early prototype of SchemeBBS was written in Guile (without Artanis)
Icing on the cake, kotatsu is now free software: https://gitlab.com/ison2/kotatsu/-/blob/master/LICENSE
Congrats >>12-sama, you have liberated two anonymous BBS software this week!