One of the first steps for researching Japanese classical literature is reading Japanese historical manuscripts. However the reading process is not easy, and time-consuming since a set of characters used in those manuscripts contain different characters from those currently used. There have been several attempts to read Japanese historical manuscripts. We proposed a framework to assist the human process for reading Japanese historical manuscript. It formulates the process as a constraint satisfaction problem, and a constraint solver in the whole system, was experimentally implemented as a UNIX command. In this paper, we added a Web service layer to the solver to realize loose coupling between the solver and the other subsystems. Thanks to the loose coupling, any programming language can be used for implementation of other parts of the whole system. In addition, the constraint solving Web service can be public through the Internet. We experimentally confirmed the solver as a Web service is faster than the that as a UNIX command if both the solver and a client are connected to a same local area network.