Common people generally don't use engagement bracelets, they just simply finish with marriage bracelets.
But if they're reasonably affluent, there is a custom of seeing their children off with engagement bracelets.
In my case, since there is magic liquid metal as material, I can use a pair of self-made ones.
"I see. Sensei is surprised, you see. I thought, 8 year olds couldn't possibly be getting married."