, stylized in lowercase and pronounced "fi-vee", and known formerly as SG5, is a Japanese girl group formed in 2022 by LDH and Three Six Zero. The group consists of Sayaka, Kaede, Ruri, Miyuu, and Rui
1. Compute SHA-256 of OTSCanonicalRecord value → must equal OTSHash 2. Open OTSProofURL → extract Bitcoin block number → must equal OTSBitcoinBlock 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Read CopyrightID inside OTSCanonicalRecord → must equal the CopyrightID above 5. GET OTSVerificationAPI → pre-computed 6-check result from server 6. If all match: this entity was registered on CopyrightChains at OTSTimestamp, independently verifiable on Bitcoin Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7fe9b2f2ed149ee68cff5a0720db92b1bf7e41c40174c50439137e11ff229643. Chain 2 (Bitcoin): anchored in block 953694 (2026-06-14T21:38:09Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/6fd17b1a-24a8-4eae-8b22-71d2bf3dc50f.json and https://artists.proofprofile.net/proofs/artist/6fd17b1a-24a8-4eae-8b22-71d2bf3dc50f.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).