susten Raises ¥1B Series A to Scale Quantitative Asset Management Platform

susten Closes Series A

susten Capital Management, an independent Tokyo-based investment manager, has raised a Series A round of 1,000,000,000 JPY. The round closed on September 18, 2026, with participation from Firstlight Capital (ファーストライト・キャピタル), Japan Post Bank (ゆうちょ銀行), and The Ascent Group. No lead investor was disclosed.

What susten Does

Founded in 2019, susten creates and manages quantitative investment trusts and runs SUSTEN, an automated discretionary asset-management service for retail investors. The service is supported by an AI tool that explains fund products.

The company was founded by two former Goldman Sachs Asset Management portfolio managers. It holds its own investment-trust management license and handles fund creation through distribution end-to-end. susten also holds a patent for its NISA-optimization technology.

Funding Details

• Round type: Series A
• Funding amount: 1,000,000,000 JPY
• Funding date: September 18, 2026
• Investors: Firstlight Capital (ファーストライト・キャピタル), Japan Post Bank (ゆうちょ銀行), The Ascent Group

Growth Trajectory

susten's assets under management surpassed roughly 13 billion yen in August 2026, which is 3.3 times the level at the end of 2025. This growth reflects increasing adoption of its automated discretionary asset-management service among retail investors in Japan.

Market Context

susten operates in Japan's retail asset-management market, where NISA (Nippon Individual Savings Account) programs have driven demand for accessible investment products. The company's combination of quantitative fund management, an automated discretionary service, and an AI explanation tool positions it to serve retail investors seeking simplified access to fund products. Its proprietary NISA-optimization technology, for which it holds a patent, is a differentiator in this space.

What to Watch

With fresh Series A capital and backing from investors including Japan Post Bank, susten is positioned to further scale its assets under management and expand its automated asset-management offerings. The company's end-to-end control over fund creation and distribution, combined with its investment-trust management license, gives it a full-stack position in the Japanese retail investment market.