Hayward is about 5 times smaller than Tokyo.

Tokyo is approximately 619 sq km, while Hayward (map shows its 16 named neighbourhoods; the area covers the whole city) is approximately 119 sq km, making Hayward 19.17% the size of Tokyo.
Tip: This to-scale comparison of Tokyo vs. Hayward uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.