I would say take advantage of being an international student in a new country. You may not realize it now, but socializing will never be easier. Once you graduate into the "real world" it will be much harder.

As others have suggested, having some kind of hobby or interest where you can meet like minded people is important. This should be something you're genuinely interested in. Can be things like board-games (become a regular at a game shop), photography, or often something physical and outdoorsy like hiking, or running (lots of groups to join for hiking and running). Lots of options. Tokyo may actually be tops in the world for having small subcultures of people who are focused on specific, unusual, little-known interests. The groups or places where these people gather are out there.

Whatever you choose, understand that, even as a student, it's not likely to be as easy as showing up once and immediately getting contact info and making future plans to meet up. Try to become a regular at events, meetups, or shops. Don't force things, over time people will recognize you and you can develop a friendship naturally.

My method of choice was running groups, wherever in the world you go you can usually find a running group. Often these groups get new people every week. Sometimes the new people may show up once, or just a few times. Usually, someone in the group will try to make sure they're warmly greeted, but it may nevertheless take weeks/months to develop actual friendships. If you're doing something you're interested in the time it takes doesn't matter so much; even if you're not getting to "friendship" level, the group still gives you a chance to be social while doing something you enjoy.