It’s signed “Shozui” but the signature isn’t genuine. It’s a nice enough looking piece, my guess is that it’s likely a Meiji piece done for export. I don’t even think this exact alloy combination existed during Shozui’s lifetime. When you ask what school it belongs to, that’s a difficult question. It doesn’t really belong to any school because it’s “Hamamono” (Mass produced for export – even though in this case the workmanship is excellent) as opposed to the Hamano school which it imitates. If it were unsigned, I would have called it “Imperial Academy School.” What it is NOT is a Hamano school tsuba by the founder Hamano Shozui. If you want to see what authentic Shozui work looks like, see
https://yuhindo.com/otsuryuken-miboku-soroikanagu/