Source of source: https://ads.nipr.ac.jp/vishop/#/extent

It's a little bit baffling. It's not like they couldn't have predicted this server load. I know it's tricky to foresee bottlenecks in some situations but them adding caching (a very basic thing for scalability) at the last minute belies a lack of either experience, forethought, or knowledge, I am not sure which.