Best App for Travel in Japan

So i had a trip to Japan last year, 2017. it was my first trip to Japan and the apps are very helpful to me. most importantly, you don't need to have cellular data or wifi to use the apps. yayy to offline apps, as wifi and data drain battery drastically.

These are the apps i installed prior to my trip:

1) MAPS.ME
2) tokyosubway

1) MAPS.ME

it's a offline map. you may bookmark the places you wanted to go beforehand etc. and you don't even need cellular data to use the map, you just need to turn on your 'Location'. oh, and also please remember to download maps prior to your trip. 

2) tokyosubway

you can search about the transfer route, the cost, and you don't need data too! you may also search for the landmark and nearest station will be shown. 

3) and for the Japan Wi-Fi app, I didn't really use it. not really useful to me.

The two apps stated are best app ever!