The Euclid mission will study the growth of dark matter structures with cosmic time after its launch in 2022. The ongoing Ultraviolet Near-Infrared Optical Northern Survey (UNIONS) will be a legacy imaging survey that will provide answers to some of the most fundamental questions in astronomy, including the properties of dark matter and dark energy, the growth of structure in the Universe from Galactic to cluster scales, and the assembly of the Milky Way. Multiwavelength coverage is essential for a wide range of science such as stellar population studies, and is critical for precise photometric redshifts for Euclid and UNIONS. Time has been allocated on CFHT and PS1 and 2 to cover uri filters with a goal of 4800 square degrees by the end of 23A. This proposal is to cover 4400 square degrees in the g-band with HSC. The result will be a legacy survey for the Northern sky.