Describe a person you used to know but have lost touch with

The person I'd like to describe is a boy called Kirill, who was my closest friend in primary school. We met when I was seven, on the first day of school, because he sat next to me, and from that moment we did everything together. We played football in the yard, shared our lunches, and even had matching bicycles.

We lost touch when I was about twelve. Kirill's father got a new job in another city, and his family moved far away. At the beginning, we wrote letters and talked on the phone a few times, but as time went by, we both got busier with new schools and new friends. Our messages became less frequent, and eventually they stopped. There was no argument or anything like that; it was simply a case of distance and different lives.

I'd definitely like to contact him again. Sometimes when I look at old photographs, I wonder what he is doing and whether he still remembers the little treehouse that we built together. I have tried searching for him on social media, but his name is quite common, and I couldn't be sure which profile was his. My mother thinks she might still have his family's old address, so I plan to ask her.

I'm a little nervous, because we are both very different people now and perhaps we would have little in common. But I think it would be worth sending a message. At the very least, it would be nice to say thank you for a wonderful childhood friendship, and if it goes well, perhaps we might even meet up.