FinWiki
日EN中

bitcastle LLC — Overseas Unregistered Crypto-Asset Exchange Targeting Japan

Confidence: Likely Updated 2026-05-19 Review by 2026-08-08 Sources 5 Machine-translated Original (JA)
#fintech#jp-foreign-exchange#fsa-warned#unlicensed#bitcastle#japanese-led-offshore
On this page

Wiki route

This entry sits under exchanges index. Read it with FSA crypto-asset exchange registration system — numbering, Local Finance Bureau jurisdiction, and registration requirements for adjacent context and Japan financial regulation — legal framework for tokens, crypto-assets, and payments for the broader system boundary.

No Japan FSA registration · Unregistered overseas-based operator · Warning notice issued 2024-11-28

1. Corporate Entity / Shareholders

  • Trade name: bitcastle LLC
  • Registered address: Euro House, Richmond Hill Road, Kingstown, St. Vincent and the Grenadines
  • Established: 2019年 (initially founded in Singapore, later relocated to St. Vincent)
  • Representative: Yoshimitsu Sekine (“Sekinemon”) — Japanese entrepreneur
  • Parent company / Listing: Unlisted. A business entity of BLITZ GROUP (Mr. Sekine is CEO)

Distinctiveness: Among crypto-asset exchanges that became targets of overseas-unregistered warnings, the case of bitcastle LLC is distinctive in that the representative is Japanese and is explicitly named in the FSA warning notice. The usual warning targets (KuCoin, Bybit, MEXC, etc.) are foreign companies under foreign management, and it is rare for an entity with a Japanese representative to receive a warning for operating, unregistered, toward Japanese residents (for framework details, see FSA warning-letter issuance system for unregistered foreign crypto-asset exchanges (2018-2025)).

2. Licenses / Registration Status

  • Japan FSA (Financial Services Agency) crypto-asset exchange registration: None
  • St. Vincent and the Grenadines is a jurisdiction without a comprehensive licensing regime for crypto-asset exchange business. Registration with the FSA differs from a de facto license.
  • JVCEA (Japan Virtual and Crypto assets Exchange Association): Non-member
  • Registration under Japan’s Payment Services Act: None

3. Supported Currencies

  • Number of supported assets: 100+ (disclosed; date unknown)
  • Major assets: BTC, ETH, SOL, XRP, and other major altcoins
  • Crypto-asset CFD (FX): 50+ types
  • Spot trading fees: 0.02% for both maker and taker (foregrounding low cost as a selling point)

4. Scope of Business

  • Spot trading: Available
  • Crypto-asset CFD / FX: Available (maximum leverage, etc., not disclosed)
  • Fiat-currency deposit: Details of yen-denominated direct-deposit channels not disclosed
  • Japanese-language support: Japanese UI and support available (marketing foregrounds Japanese-language support)
  • Characteristics: Appeals with its Japanese founder and Japanese-language support, using the founder’s profile as a social-media influencer to acquire customers

5. Market Share / Trading Volume

  • Registered users: The company claims “over 100万” (date and definition unclear; no public materials)
  • Trading volume: Not disclosed
  • Customer base: A small exchange primarily targeting Japanese speakers and Japanese residents
  • Position among competitors: Emerging / niche. Like major global exchanges (Bybit, MEXC, etc.), it accessed the Japanese market without registration, but at a far smaller scale

6. History / Major Events

PeriodEvent
2019年Yoshimitsu Sekine established bitcastle in Singapore
After establishmentRelocated and registered the entity in St. Vincent and the Grenadines
2022年 (some sources)Described as having begun formal operation as a corporation (sources vary on the year of establishment)
2024年11月28日FSA issued a warning notice: Under the Payment Services Act, named “Bitcastle LLC, representative Yoshimitsu Sekine” as a party conducting crypto-asset exchange business without registration. Issued simultaneously with KuCoin, Bybit Fintech Limited, MEXC Global, and Bitget Limited (a total of 5社). Basis: Crypto-Asset Exchange Operator Relations III-1-6 (2) ②
2025年4月25日The Local Finance Bureau (lfb.mof.go.jp) also published the company as a party conducting financial instruments business without registration (securities / FX related)

Content of the warning: The FSA noted that the company “conducts crypto-asset exchange business, via the internet, with Japanese residents as counterparties,” constituting a violation of the Payment Services Act. Among the 5 社 issued simultaneously, the only one whose representative’s real name and nationality (Japanese) were widely reported domestically in Japan was this company.

7. Strategic Developments

  • Even after the warning was issued, as of 2026年 the Japanese-facing website and services continued (various review sites posted the company’s campaign information after the spring of 2026年 as well)
  • There is information that, as of 2026年5月, bitcastle FX (crypto-asset CFD) was being additionally rolled out
  • Continues integrated marketing of personal brand and services through Japanese-language social media (Instagram, approximately 1.3万 followers, the account commonly known as “Sekinemon”)
  • User reviews regarding withdrawal refusals and service quality exist across multiple media outlets (as of 2026年)
  • Yoshimitsu Sekine (“Sekinemon”): Japanese entrepreneur, BLITZ GROUP CEO, bitcastle LLC representative. Claims to have made approximately 100 × returns from an early investment in Solana (SOL), posts crypto-asset information on social media (X, Instagram), with over 20万 followers (as of 2024年). Has a TV appearance history during the Sanae-token uproar (2023年), and is also mentioned in peripheral ventures such as World Peace Coin. Claims to reside in Singapore and operates multiple offshore business entities.

Sources