Sim card or wifi router?

[N4E.SI]

last year moi went Hoikaiddo. my happy roam pre-paid sim card totally didn't work at all!

activated auto-roam also didn't work. why ah? whole trip no internet except back in hotel using wifi

so far the most reliable for me is changi wifi. neber fail one. juz that very mafan bring it around like carrying a piece of brick in my pocket

 

[BigMonkey]

most likely need to setup APN.

 

[endlssorrow]

We planning SIM card coz easily.
Don’t have to carry additional router inside bag?somemore don’t need to walk as a group

Anyone can advice?
Is it better to buy a prepaid sim card in Japan or rent a wifi router instead?
Length of trip is 12 days and will be travelling solo.
And also considering that I'll be outside and on the move most of the time (more than 10 hours).

My previous experience when using wifi router in other countries is that it needs constant charging and the battery ran out quite fast.

If sim card. Any particular ones to recommend? I will require minimum 12 days of usage.