IPv6 is designed to solve the exhaustion of the address space, which are one of the biggest problems in the current Internet. The WIDE project has been involved in IPv6 since its early stage, and organized the KAME project in 1998 in order to accelerate its deployment. The KAME project has provided a free, specification-compliant implementation of IPv6 on BSD variants. With its quality and the continuous efforts on it, the implementation has established the position of a reference to IPv6, and has been adopted in BSD variants and in several commercial products. This paper first gives an overview of the IPv6 specifications, including its plug-and-play function, API, DNS, security and transition tools. It then describes the implementation by the KAME project. It is based on the BSD's original network stack, but explores some original enhancements for Neighbor Discovery or IPv6 addressing. Finally, it explains what is missing for the next steps of IPv6, concentrating on plug-and-play and security. The KAME project has joined, and will continue, the standardization and implementation efforts on the new issues.