@TurboshitterYou'd have to go and ask Masaki if he wants to swap out to assassin, or lancer. If you like I can recommend some ideas like Kotaro Fuma (Who gets a boost from being in Japan). Lancer should be much easier.
@TurboshitterHonda may very well be too strong a character to play in his home turf in my opinion. Honda is already strong, and being in Japan just compounds that fact. It would depend on how you play him to not make him broken. Hanzo may be slightly more manageable as the enemy assassin has quite the nasty noble phantasm.
@TurboshitterIt would be a poor weapon choice for assassin as spears are longer weapons but if that's your choice in weaponry then do be it. He'd obviously be weaker than a standard lancer who openly wields his or her weapon. As a Lancer (who I believe would be more deserving of a different character but if Hanzo has a history with the weapon all the same) she would retain her ability of stealth and what have you but would be far below the other assassin in terms of actually staying that way as assassin carries the perks of stealth and all.