Luxury Co-Owned Mountain Villa 'Seren Collective OAK' Completed in Karuizawa Hilltop with Panoramic Views of Mount Asama

June 16, 2026

Vortex Corporation

Vortex Corporation (Head Office: Chiyoda-ku, Tokyo; President & CEO: Fumihiko Miyazawa; hereinafter "the Company"), a firm specializing in asset formation consulting centered on its proprietary "Divided Ownership Office®" model, announces the completion of 'Seren Collective OAK,' a luxury co-owned villa developed in Karuizawa Town, Nagano Prefecture.

The property was designed by architect Kentaroh Ishida, known for international projects, and was created to harmonize with Karuizawa’s rich natural environment. It marks the third villa in the Company’s 'Seren Collective' series.

'Seren Collective OAK': Exterior Rendering (Aerial View)

【Seren Collective Series】

'Seren Collective' is a new model of villa ownership where a single villa is co-owned by multiple owners, each entitled to a fixed number of annual stays. Ownership is registered as shared real estate rights, enabling future inheritance, transfer, or resale. The model supports diverse uses, from corporate welfare, hospitality, and team-building to personal resort lifestyles.

'OAK,' now completed, stands out within the series for its elevated hilltop location and the architect’s ambitious design.

Seren Collective OAK Official Website

【Property Highlights】

① Premier Hilltop Location in Karuizawa

Located approximately six minutes by car from Karuizawa Station, the property sits on a spacious 4,274㎡ (about 1,292 tsubo) site, offering expansive views of Mount Asama and ski slopes. Large floor-to-ceiling windows on both sides of the living area frame seasonal mountain landscapes, creating a seamless connection with nature.

② Organic Architectural Design in Harmony with Terrain

Designed by Kentaroh Ishida (Ishida Architects Studio Inc.), who studied architecture in London and served as an associate at a global architectural firm, the building follows the natural contours of the land with gentle curves. This design integrates the surrounding forest scenery and elevates the stay into a holistic experiential journey. Contemporary art pieces are thoughtfully placed indoors, creating a unified space where nature, architecture, and art coexist.

③ Comprehensive Amenities

Living & Dining: Floor-to-ceiling panoramic windows on both north and south walls offering views of Mount Asama and ski slopes

Bathrooms: Two large stone bathtubs (one doubles as a cold plunge), dry sauna with löyly system, steam sauna

Bedrooms: Master bedroom plus two guest rooms

Kitchen: Custom-designed kitchen carved from artificial marble

Garden: Outdoor dining area, fire pit table, water basin

④ Efficient Asset Utilization Through Co-Ownership Model

The villa is divided into 12 ownership shares. Each share grants the right to 28 annual overnight stays (6 fixed dates and 22 flexible dates). The operator handles all management, including cleaning, maintenance, and major repairs, allowing owners to focus solely on their stay experience. Additionally, owners can freely access other properties in the 'Seren Collective' series at no extra cost.

'Seren Collective OAK': Interior Rendering (Left: Living Room, Right: Terrace)

'Seren Collective OAK': Interior Rendering (Left: Dining Room, Right: Bathroom)

'Seren Collective OAK': Interior Rendering (Left: Water Basin, Center: Kitchen, Right: Bedroom)

'Seren Collective OAK': Interior Rendering (Left: Terrace from hallway, Center: Sauna, Right: Terrace at night)

Property Overview

Future Developments

The Company will continue to expand its 'Seren Collective' series, offering real estate services that combine investment value with experiential quality. Additional properties are scheduled for completion, enriching the portfolio to meet diverse owner lifestyles.

【Company Overview】

Vortex Corporation

Founded in 1999 by Fumihiko Miyazawa (President & CEO), Vortex Corporation provides innovative financial solutions for businesses. Guided by the purpose of 'bringing new norms to management and realizing wealth redistribution to correct social inequality and division,' the company addresses societal challenges such as economic stagnation due to wealth concentration and urban-rural disparities through innovative thinking.

To date, the company has contributed to clients' financial stability by providing non-core-business revenue streams and highly liquid, sellable assets. Its service portfolio includes 'Divided Ownership Office,' fractional real estate products 'V Share®,' the in-house secondment program 'V Turnship®,' and the luxury co-owned villa series 'Seren Collective®.' All business units continue to grow. As of March 31, 2026, the company employs 821 people, with headquarters in Tokyo and branch offices in Sapporo, Sendai, Niigata, Kanazawa, Nagoya, Osaka, Hiroshima, Matsuyama, Fukuoka, and Kagoshima. For the fiscal year ending March 2025, it reported sales of 103.8 billion yen, operating profit of 13.4 billion yen, and owned rental real estate assets valued at 69.4 billion yen.

・Corporate Website: https://www.vortex-net.com/

※ 'Divided Ownership Office,' 'V Share,' 'V Turnship,' and 'Seren Collective' are registered trademarks of Vortex Corporation.