There’s a few things that could happen to you in Shinto belief. Nothing exceptionally good either as there is no actual heaven.
When one dies, the spiritual energy is released from the body. Then that spirit would go into the underground realm called the Yomi no Kuni. If you have been following my videos, you would know that Yomi no Kuni is the land of the dead where Izanami no mikoto, which is one of the god that created Japan, ended up in when she died. The land of the dead is a gloomy, dark and most probably in a different plane and dimension underground.
There’s a river separating the land of the living and the land of the dead. Pretty much like Hades.
Everyone and everything with a spirit and dies would end up there and live there forever. There are no punishments nor rewards. But with some exceptions. As long as you haven’t eaten anything in the world of Yomi, you won’t be their permanent residence. But that would be almost impossible because when you’re new, you would be in a state of confusion and wont remember much.
Of course being an exceptional person that caught some of the God’s or Kami’s eyes might just land you a good deal to live in other worlds such as the Takamagahara where most of the dieties resides in.
Though, it is believed with proper rituals or festivals, these spirits could come back to the present world in spirit form.