A toy system for sending and reading hidden secret messages including a toy dart or arrow launcher using a dartarrow with a surface for preprinted or written messages, a pen if the message is to be written, and a decoder structure. The first and second mounting end portions include a first or second thickened mounting area, respectively, from which the first or second strengthening rib extends to the top and bottom layers. A non-cutting intersecting ridgeline area extending between adjacent cutting edge sections on one end surface is located adjacent, via the peripheral side surface, to at least a part of the corner cutting edge and the major cutting edge of an associating cutting edge section on the other end surface.