There is a free landside shuttle bus that connects T1 and T2 but I don't know if it's worthwhile given the vagaries of planes being late and such. It might still be the best option if you really want to meet at Narita.

The airside shuttle between the terminals will require an ongoing ticket, so you can't use that.

Absent having workable Japanese mobiles, you could agree that one of you take the shuttle to the other terminal and then just meet at, say, the arrivals area. It's not that small an arrivals area in either terminal, so you might want to refine it down. Decide who is going to take the shuttle to where and I'm sure we'll have a recommendation.

Another possibility is just to agree to meet up at your hotel. This works better if it turns out that one of the planes is late.