This have to depend your Travel Insurance cover policy. Some including Flight delay some don't.
But most Insurance Delay start count 5 - 12 hour above.  Less Than 5 Hour you cannot claim anything.  Depend how premium you buy your insurance. Even the world most premium one also start as 5 hour delay.

Jus reached haneda, damn lots of ppl, donno can buy the pass or not

Don-Quijote (Donki)

If by snacks you mean those various boxed snacks that tourists like to bring back as souvenir (eg Tokyo banana), the Tokyo skytree mall and diver city mall at odaiba are two places with a ton of variety.

Food, you can still sacrifice. Buy cheaper food from Family Mart or anything but transportation you cannot save.
Well, as you know Japan transportation is very efficient and obviously that comes with a cost.
I spent around 4.2k for my 9 days trip for food, transportation, souvenirs and gifts for the special one.
Souvenirs are not cheap in Japan. Also, I stayed at my friends' house so those costs didn't cover accommodation.

RM600 for 6 days food. Means each meal you cannot spent more than 1000 Yen // RM30.
Like this your one whole week only can eat Sukiya (refer to page1) or Yoshida or Family marts // Dawson Bento set only.

I had 8-piece sashimi for 1000 yen at Tsukiji Market. I don't know how to appreciate sashimi but since I thought I was in Japan should try once before I left.

Ya, it's expensive and the only benefit is you can get the product before departure.

Have look through all Global Advance, eConnect and Pururu, but my arrival time is 22:30 at KIX and I got to leave the airport next early morning , so delivery to KIX post office is not possible as their working hours is 9am to 5pm. 1st night stay in temple lodge Koyasan.

Since I need internet connection after leaving the airport. Think I will just settle with the So-net data sim which can be purchase  from the vending machine 24 hours in KIX.

Anyone use this before? Compatible with Galaxy Note 4?

RegentCid, wanna ask for your advice on the minimum num of days travelling in Narita airport. I am kinda limited on budget rm1500, will it be sufficient? Mostly backpacking, overnight at airport and go sight seeing.

Since you can find Sushi Zanmai here in Malaysia(raw material and chef is different) but why not give Midori a try