You almost certainly don't need a transformer, since 100V instead of 120V is almost certainly within the tolerance of the device, particularly for a simple heating device like a hot air brush.
Fun fact: even in the US, that "120V" can actually be anything between 104V and 126V at the "utilization point" where you plug in your device.
Without help from a friend in Japan or using a proxy, it will be difficult to get concert tickets, which are hard enough to get in Japan.
Currently, there are no general sales tickets available, and they have yet to announce the date.
On the site you posted, the following was posted along with the concert schedule:
I'll work on this answer or I'll change it to an answer wiki if anybody prefers. Please let me know. This is just a rough version so far...
FamilyMart : 3 X 20 minutes per day via email registration. May have seats and power! Look for イートイン "eat in". Can be confusing to get working and staff can't help.
Lawson Station : Easiest konbini Wi-Fi to use by far!
7-11 and Starbucks also have free Wi-Fi.
(I can't recall if McDonald's has Wi-Fi, but they tend to in most countries)
There is also this "Free Wi-Fi Passport" offered by Softbank:
According to the site you only need to provide "mobile phone number, password, gender and age group". For that to work, ...
TL;DR: If you enter a fan club/general "raffle" (抽選):
you enter the raffle;
you get notified if you're successful;
if you're successful, have a friend pay at a FamilyMart;
pick up your tickets at a FamilyMart when you arrive in Japan.
If you buy a general sales (一般発売) ticket:
you go to eplus and buy your ticket;
you pay with a JCB card or have a friend ...
Yes, ORIX offers a Car2Go-style car share/short term rental system. The service is Japanese only, but here's a detailed English blog about it: https://bestlivingjapan.com/japan-carshare-orix/
While you don't need a Japanese license, it does require signing up in advance and receiving a dedicated card by mail for unlocking cars (no phone apps here), so it's ...
I suspect the problem is one or both of these two:
Are you sure you've got the right website? Flight NH805 is on All Nippon Airways (NH/ANA), not Japan Airlines (JL/JAL). There is also an ANA subsidiary called Air Japan, but AFAIK they don't fly to Bangkok and their flights are effectively indistinguishable from mainline ANA anyway.
Are you sure you've got ...
You will need to show a passport on three or four occasions.
On check-in. Here, the agent has to confirm that you meet the requirements to be admitted to Japan and that you are the person on the booking. You want to show the agent your Japanese passport as it confirms you are eligible to enter Japan in the easiest way possible. (In case the romanisation of ...
Hopefully this gets to you in time. I myself have traveled the Shimanami Kaido, but not the Tobishima Kaido.
After some research, this site(in Japanese) says that you can travel the Tobishima Kaido to the end, Okamurajima, and from there, take a ferry which goes to Imabari. The site says the ferries are bicycle friendly. And of course you can also come from ...
You are most likely not going to find a suitable consumer-targeted transformer to go from 100 to 120 V with their respective tolerances. Most devices that people are likely to take with them on a trip from Japan to North America or vice-versa are well-suited to handle both nominal 100 V and nominal 120 V. While there is a (small) market for 100/120 V to 230/...
If you don't mind something heavy, you can also find transformers for this purpose on amazon.jp. They all look like typical made-in-China adapters of dubious approvals status. Also very heavy but maybe acceptable for a long stay. The advantage is that you could order it in-country if your gadget does not work properly.
If your Japanese is good enough to ...