It's quite easy to navigate Haneda airport and Shinagawa station without any Japanese. Unless your partner has special needs, I don't think you need to worry.

For some reassurance, I recommend this video of an Australian family arriving at Narita ** and taking the train into Tokyo. As you watch, take note of all the signage that's in four languages. Skip to 2:50 where the girl says "Guys, we're trying to catch a train. Nothing is in English and it's so confusing ... We're trying to find which train to get on. I'll update you if we get on the wrong train, because literally nothing is in English, so we don't know where we're going. We're just following colors at this point."


** The situation at Haneda is much the same. Virtually everything is signposted in English.