[question]What are these two Japanese coins?

Many years ago, when I was living in Germany, a Japanese friend of mine gave me these two coins. I don’t know what they are. One of them does say “Tsukuba Expo ’85,” so I think that one might be a special coin for an event. I have a link to both the coins, the first one shows what I perceive to be the first side of the coins, and then the next one shows what I think is the second.

If anyone here knows what these two coins are, I would be grateful for an explanation. Thank you.

[https://imgur.com/a/7RR0ZSH](https://imgur.com/a/7RR0ZSH)

https://www.reddit.com/r/japan/comments/13dsnk7/questionwhat_are_these_two_japanese_coins/