While (as I commented above) this is highly subjective, let me give you some general calculation:
Your 3000 EUR are roughly 390'000 Yen.
The very very decent version
I chose the Mitsui Ginza Hotel for location and took the smallest single room there for 15'500 per day (16'500 on Sundays) for overall 218'000 Yen.
If have breakfast in a Sarbucks you spend about 1000 Yen, so another 14'000 Yen is gone. Let's take 1'500 Yen for lunch, so 21'000 Yen for the week and good quality 8'000 Yen for dinner in average which makes 112'000 Yen. All in all this will make 365'000 Yen. This will leave you with 25'000 Yen for subways and souvenirs etc.
The issue here is that you might run into taking taxis (no trains late at night) which are somewhat expensive and other stuff, so you might run into a shortage in the end. Careful planning is important on this budget. Also taxes etc might be a very tight fit for this but if you manage your costs properly and balance a bit for some days you can have a very decent high-class stay in Japan for 3k Eur.
The budget version
Cheaper version would be a cheaper hotel like the Sakura hotel chain for about 6'000 a night coming to 86'000 for the 14 nights.Breakfast at a convenience store for 500 Yen (7'000), a budget lunch for another 1'000 (14'000) and a much more reasonable dinner for 5'000 (70'000) will get you there with 177'000 Yen spent.
You can check some average prices in restaurants here and Convenience stores to get an overview.
Note: There is no weekly pass for Tokyo Metros. The minimum is 1 month and costs 168'000 Yen - which does not make sense for you.