Well, I think it was said in the script that the transformation into Lynx took 4 years, and that Wazuki was "corrupted" by the Frozen Flame but not driven "mad" by it.
Serge made contact with the Frozen Flame in 1006 A.D., but Wazuki didn't transform into Lynx until 1010 A.D. and only then did he attempt to kill Serge at Opassa Beach. I think that is compelling evidence to suggest that Wazuki was in his right mind at least for the trip back to Arni Village, and probably for most of those 4 years too (although a slow descent into madness is likely).
Ah, I see. I'll have to take your word on the four years thing. But yeah, that seems fair enough.
