If a PC has Weapon Prof and Focus (Katana) and Weapon Adept (Versatile Design), does he qualify for Ascetic Style (Katana) as long as it's used for a Versatile Design (Monk) Katana?
Or would he need Weapon Focus (quarterstaff), and five levels of Monk, to be able to use his katana with it?
Strictly by RAW you have to choose a weapon listed in the group since its only the modified Katana that is a Monk weapon. Then once you hit level five you would be good to go.
That being said a GM might allow it with the understanding that while you may have chosen Katana only ones modified will work.