Telecom Square Phone Rental

Okay, so my trip is coming right up and I'm trying to nail down details including a phone situation.I'm coming into and leaving Haneda so I was looking at the rental counter options they have there and I found "Mobile Center" (Telecom Square) and they look like they have what I want.

Basically, I want to rent a phone to use for emergency purposes only (because the price to use it with my own cell company is outrageous) and most importantly to use as a wifi-hotspot so that I can use google maps, translator apps, and other various apps to help me along the way on my own phone as well as the phones of the others who are in my group. I decided that the phone was probably a better choice than just the wifi router they offer because that way we can use it to call if we need to.

My question is does anyone have experience with this? How well do they work, how's the battery life, etc. Is the router better than the phone or are they the same? If there are any alternatives I would love to hear but keep in mind that I get into Haneda really late and I don't want to get stuck not having any connection when I have no idea where to go... so I'd prefer the option be in the airport. I'm only visiting for 11 nights so long term options would be wasteful.

Thanks for the advice!

I also just learned about Rentafone, is this service better? I've heard good reviews. The prices are great; even though they don't have a phone that can be a hotspot it's still $2 cheaper a day to rent both a wifi router and the phone. Plus they don't charge extra to deliver to the hotel, which I was going to do because I get in so late.