Hello I'm new to this forum and to bonsai. I've read a lot about soil, and I always come across kiryu and akadama soil. It's very hard for me to find it in my country (Sweden) or if I find it, it's really expensive. About €30 for 10 litres. Are there any other kinds of soil you can use to replace akadama and kiryu?

Of course there is- search this forum for anorganic soil or substrate. Terramol ( cat litter) , zeolite, perlite, clinoptilolite, etc etc etc...
but be careful , you opened Pandora's box with this question...

Where in Sweden are you?

The thing is, soil is a hot debate every time and there are a not of different opinions on what us the best. The different opinions is most likelly based on different climate and care. Sweden is a long country with many different climate zones. I am in western Sweden and have made my own conclusion for substrate and care. Bonsaisällskapet have 4 different branches, a normal corona Free year it is well worth the member fee to enlarge your network.

Tropfrog wrote:

Where in Sweden are you?

The thing is, soil is a hot debate every time and there are a not of different opinions on what us the best. The different opinions is most likelly based on different climate and care. Sweden is a long country with many different climate zones. I am in western Sweden and have made my own conclusion for substrate and care. Bonsaisällskapet have 4 different branches, a normal corona Free year it is well worth the member fee to enlarge your network.

I live pretty close to Stockholm. Thank you!

Bonsai soil can be anything so long as it absorbs water and holds it until next watering and so long as it drains well. A guy here lives by a cement factory and uses something he gets from their discards. And as long as it last until next time the tree wants repotting.
Cat litter is said to work, but you want something without perfumes or other additives. Anything that makes the tree live is good. Unfortunately, you don't find out if a mix kills the tree until too late, but if you go for well draining you will be ok.