K2K: the precursor experiment that fired Japan's first neutrino beam to Super-Kamiokande
Before T2K, before Hyper-Kamiokande, there was K2K — the KEK-to-Kamioka experiment that ran from 1999 to 2004. It was the first accelerator-based long-baseline experiment to confirm neutrino oscillation, paving the way for everything Japan's neutrino program has done since.