Well he did say "maximize Japan experience" - that would include the following:
*Touring around. Gunna cost a LOT of cash just to get around if he's serious about going from place to place. Even more if he doesn't know what he's doing and gets a taxi
*Buying souveniers: Oh man. talk about money money money
*Eating out: That's Unagi (eel) season so be prepared to spend (if you go to a GOOD place) about 2,500 yen for a meal. That alone will be 17,500 yen right there for nice evening dinners. More if he goes to try something unique like fugu (look at 12,000 per dinner per person - just had that experience while taking 9 clients out for Fugu in Asakusa... fuck me...)
*Entrance costs for museums: Pocky museum, Ramen museum, Salt museum, Pachinko museum, Gundam museum, etc etc etc. Each costs between 700 and 1,500 yen.
*Snacks throughout the day + liquids so he doesn't keep over: Tack on another minimum 1,500 per day just to keep you hydrated.
*Shopping: Not souvenirs, just cool shit for yourself. Japanese electronics and gadgets, sex sleeves (Onna-holes) if you're a single guy and desperate, DVD's, manga, etc.
*Money for liquor if you like to go out and party it up: Tack on 8 to 10,000 yen per 'outing'.
*Cash for Maid Cafe's if he's going to try it: Entrance into most in Tokyo is roughly 2,500 yen ontop of the price of your drinks and food. I suggest my buddies establishment in Akihabara called 'Friendly Fire'. Walk straight North on the West-entrance of Yodobashi Camera, it's about 2.5 blocks up and on the right. 3rd floor (up a huge horrible stairway)
*13,000 or so if he wants to see some porn-stars dancing in Asakusa (Maria Ozawa, Yuko Kazuki, Yummi Ichikawa, Victoria or 'Vicky' Slavik). Even more if you want a lap-dance.
So... that's a general idea. It's not mentioning the hotel/hostel cost either or anything else you might need cash for. If you wear glasses, you can pick up some awesome specs for 7000 yen. Super cheap compared to Canada anyhow.