The Ryujin board is very similar to the Musashi board, but not quite the same. It doesn't fall under the same naming systems as Tadao's other boards, as it was made specifically for BLAST to use as a stock board, rather than for Tadao to sell themselves.
M8 does refer to the Musashi board for the Marq series - basically speaking, it means Musashi firmware, version 8. As of yet, while the Musashi 7 firmware is used on number of different Tadao boards for different markers, Musashi 8 has only been used on the Marq boards.
You can download the Ryujin board manual here: -