I've gotten this question a few times from folks at home, so I figured I'd lay out what a typical week in my life looks like:
-Sunday: Catch up on the homework I didn't do over the weekend, occasionally go out for a mellow outing.
-Monday: Internship. Out to Akasaka to work at Six Apart Tokyo. I was just doing afternoons for awhile, but starting this week, I'll be going to the all-company meeting in the morning (mostly for my own edification), and running a little English conversation circle during lunch, so it will turn into an all-day thing.
-Tuesday-Thursday: Classes, classes, classes. Go to school, come home, eat my host mother's delicious cooking, and stay up too late on the Internet (actually, that last part applies any day of the week). Thursday night is absolute hell, because it's followed by a kanji (japanese pictograph characters) test at 9am the next day. Also, I telecommute into my internship Thursday morning, sitting in on a little chat meeting between the Tokyo and San Francisco IT teams and translating where they need it.
-Friday: Classes in the morning, quick trip home (or an hour trip home, rather) for a shower, and some sort of drinking event.
-Saturday: Much like Friday, with a jog and a little homework replacing the classes. Between Friday, Saturday, and the weekdays, I usually make it out about twice, with the standard event being your typical izakaya (traditional sit-down bar/restaurant place) party at Takadanobaba (高田馬場), the college-priced district a short walk from school.
This changes occasionally, depending on schoolwork and various invites, but life usually works out to about 5 days of studying and 2 of goofing off, producing a pretty stable budget, grades, and health level. I can easily tell that I could make life a lot easier by cutting back or not working on my Japanese classes, or much harder by increasing them. The English language classes are a joke; I think I could probably (and likely will) toss in another few credits next semester, as they take barely any work. If you're thinking about coming to Waseda, also be aware that how much time Japanese takes depends on your level and teacher; I've heard that the lower ones (I'm in 5A at the moment) tend to produce less work, but that it varies by teacher.
If you're trying to reach me by phone, the best times (translated into PST) would be Tuesday or Wednesday evening. These are my late mornings at the house, so I'm usually in a good space to chat. That said, feel free to email me if you want to talk, and I'll make time for ya.
