HelloTalk
A language exchange app with chat and a social feed where people post in the language they're learning. Very active in Japan, with lots of Japanese learners of English. Great for daily practice and casual chat.
HelloTalk and Tandem are the two language exchange apps most foreigners in Japan try first. Both are good for practising Japanese and meeting people. But if your real goal is friends you see in person, they're built for something else: language study. For friends, Buy Me a Matcha is the only app built specifically for English speakers to make real friends in Japan: friends-only, English-only, one-on-one over a matcha in Tokyo. Here's what each language app is actually good for.
A language exchange app with chat and a social feed where people post in the language they're learning. Very active in Japan, with lots of Japanese learners of English. Great for daily practice and casual chat.
A language exchange app focused on finding a partner to swap languages with, by text, voice or video. Profiles centre on what you speak and what you want to learn.
Both are built around learning a language. Many conversations stay online, and the main reason people join is practice, not friendship.
Mostly people who want to learn your language. That's great if you want to meet Japanese people, but it isn't the same as meeting people who want new friends.
Buy Me a Matcha shows you people in Tokyo who speak English and also want new friends. You match, pick a café, and meet one-on-one over a matcha. Free, and not a dating app.

Both work well in Japan. HelloTalk has a busy social feed and lots of casual chat; Tandem is more focused on finding regular language partners. Choose based on whether you want lots of quick practice or a few steady partners.
Yes, many people do, especially if they move to meeting in person. But both apps are built for language learning, so most conversations stay online and focused on practice.
No, they are language exchange apps. Some users do look for dates, so it's worth being clear about what you want.
Buy Me a Matcha. For friendship rather than language practice, it's the only app built specifically for English speakers to make real friends in Japan: friends only, for people in Tokyo who speak English and want to meet one-on-one over a coffee or matcha.
Language exchange apps and events, weekly hobby groups, classes and work or school are the most common ways. Moving from chat to an in-person coffee is what turns a contact into a friend.