What is a good place for an American to try and meet a Japanese pen pal?

If you're really looking to find someone to chat with in Japan, honestly, just skip those big formal language sites. I've had the best luck on apps like Tandem or HelloTalk. It's way more casual and you get to talk to real people who are actually interested in learning english while you pick up a bit of japanese. Just be prepared for a ton of messages because people over there are usually pretty curious about folks from the states.

Another solid way is to join some discord servers dedicated to gaming or anime, but try to find the smaller ones. You'll run into plenty of japanese folks hanging out there, and it feels way less awkward than those "pen pal" sites where everyone is trying too hard. If you just jump into a voice chat or start talking about a game you're both playing, the conversation flows way easier than trying to force a letter exchange.

Just keep in mind that the time difference can be a total pain. Since they are usually half a day ahead, you'll be waking up while they're winding down for the night. Don't get discouraged if they don't reply right away, it's just how the schedule works. Just stay chill and keep the talk light, you'll find someone cool to chat with soon enough.