It depends. How much do you depend on your laptop in daily life in your home country?
A smartphone is probably much more convenient, providing you can get around the problems of SIM cards that work here. Sorry I can't help you there.
Hell Yes i do bring my laptop everywhere i go in Japan.
Because i don't plan on returning back to my hotel until midnight. I always take the last train in, If the last train gets me in early, i just go somewhere with wifi and hangout get update my work/ social media or edit/upload pictures.
But on this last travel in March i didn't really carry my laptop to much because it was a little heavy and the size was a little bigger for my mid-small backpack, But i could have deal with it. The main reason why i didn't really carry my laptop with me because of 1) my battery was shot, it did not hold charge. 2) a lack of outlets/ in fast food places, but when i was more in south part of Japan, Tokyo, Osaka, and down to Nagasaki there was a lot of outlets plugin in fast food spots. Going from Tokyo, Sendai, and up to Sapporo, i did not see a lot of plugin spots in fast food places, and 3) Wifi, always having to register email to use, before, just have to click on the wifi and use it.