Styrax japonicus is a really great tree for Bonsai. I rarely see them for sale in Colorado. I did see a beautiful tree at a local nursery and it was very expensive. It had small leaves that looked like an Elm leaf. It just happened to be blooming when I saw it and smelled really nice. I think they would make excellent Bonsai trees. There are several different varieties to pick from including a weeping form. International Bonsai Michael Hagedorn has three excellent articles Styrax Bonsai trees. I think they should be able to help you in case you want to try one.

Deciduous Early Development Part III: Styrax by Michael Hagedorn  New 12-18-2020

Deciduous Early Development Part IV: Studying Old Styrax by Michael Hagedorn  New 12-18-2020

Deciduous Early Development Part V: Styrax by Michael Hagedorn  New 12-18-2020

Multiple-trunks and Nebari Development by Michael Hagedorn  New 11-30-2021