The Hyper-Kamiokande detector consists of a megaton scale water tank and ultra high sensitivity photosensors. The Hyper-Kamiokande detector is both a “microscope,” used to observe elementary particles, and also a “telescope” for observing the Sun and supernovas, using neutrinos.
The Hyper-Kamiokande project has an extremely rich physics portfolio that spans from the study of the CP violation in the leptonic sector and neutrino mixing parameters to proton decay, atmospheric neutrinos and neutrinos from astronomical origin. It is supported by both the HEP and Cosmic Ray communities.
The Hyper-Kamiokande collaboration is currently composed of members from institutes coming from 13 countries in 3 different continents.
A recent press release detailing the inclusion of Hyper-K in the Japanese MEXT Roadmap, and the positive implications this has for the future of the experiment, can be found here.