User blog comment:B214/General Discussion/@comment-73.46.6.122-20170505203143/@comment-29963364-20170505224629

The client from the story is from one of the many families that wield "Holy Spirit" swords called Totsuka no Tsurugi.

Since there are multiple families that possess and wield these swords, that means that "Totsuka no Tsurugi" isn't just one sword, but is actually the name of a class of japanese Holy Swords.

They aren't as powerful as "True" Holy Swords (Excaliber, Durandal, Caliburn, etc.), but are still effective against demons, evil spirits, and other "dark" beings.