I have a situation where a character goes missing for a period of months; they eventually do turn up, but given the circumstances (high school student goes tromping around in the woods and never comes back, searchers turn up nothing), they were gone long enough for people to think they were probably dead and greet their return as miraculous.
My question is, in the meantime, how and where would this person's family and friends pray for them, especially as it seems more and more likely that they're dead? The family in particular wouldn't want to have a funeral or treat them as if they're dead unless they find a body or the person is legally declared dead (which would be a certain number of years, I think? Longer than they're gone), but they're also accepting that the chances aren't good, so they're caught in the middle like "please take care of them wherever they are; if they're alive, I hope they're safe and come back to us; if they're gone, I hope they didn't suffer."
Specifically: when praying for this person, would the family be likely to use a home altar of some kind, a special object like a religious item or a picture of the person, and/or candles or incense or such, and in general if you watched them pray for the person, what would you expect it to look like? If the family and friends wanted to go somewhere to pray for this person, where would they go and what would they do?
Looked up kamidana, butsudan, and ema but didn't find how they would be used in this case. Googled variations of "how Japanese pray for missing person" and just found tsunami-related non-Japanese "pray for Japan" pages or missing-persons news stories. Also found information on the ritual for praying at a Shinto shrine; those pages said people in mourning weren't supposed to visit Shinto shrines because of the impurity of death, which just made me more curious how praying to kami or wishing on an ema would work or not in my specific case.