Sisu is a founder-friendly incubation fund founded by Ari Mir. It partners with aspiring entrepreneurs from the earliest stages of company formation, often referred to as 'day minus one.' The organization aims to help founders maximize their potential by providing guidance and support during the critical first two years of their startups. Sisu is based on the principles of Finnish culture, emphasizing determination and resilience.

Sisu invests in early-stage startups, providing services that include cofounder pairings, fundraising assistance, and foundational support for long-term value creation. The organization selects a limited number of founders each year through a rigorous admissions process, allowing for personalized support. Sisu operates without taking board seats or cofounder roles, transitioning to a traditional advisory role after the initial two-year support period.

Founders in the Sisu program receive personalized support, guidance in fundraising, and assistance in forming cofounder relationships. The program emphasizes a hands-on approach during the critical early years of startup development.