UEFI is a de-facto standard BIOS for x86 based computers. Currently, there are two types of UEFI implementations, TianoCore and closed firmware developed by BIOS vendors. The latter has problems that the users can not fix the bugs or the code shipped without enough verifications. TianoCore is an open source UEFI. However, its code base is too big in the view of booting OS. Thus, it is not suitable for embedded systems or bare metal clouds. To solve these problems, I propose yabits, a new UEFI implementation. I confirmed that yabits is small footprint and boots fast compared with other UEFI implementations.