Do Japanese people believe in angels that protect them from evil spirits, or demons?

Well, you'd have to know about the religion that originated in Japan: Shinto. Shintoism is sort of pantheistic: everything has a spirit, or 'kami'. A lot of them are larger, more powerful spirits that you could call deities, but none are as large or as powerful as the Christian God. This way, nature has balance, that may be broken by people disrespecting or angering the wrong spirits. They do use words like "demon" and "ghost" to describe a lot of spirits, but they are not demons in the Christian sense; they aren't malevolent by nature, rather they're prone to both kindness and anger, just like us. Safety from evil spirits is more up to the individual keeping the balance of nature than to any deity protecting them. All the same, kami might fight with each other. And they don't really have a heaven, just a spirit world that the kami reside in. When you die, you enter the invisible spirit world.

No, they don't have angels. Traditionally speaking, Asians believe in demons and ghosts, that some of these entities are good and some are bad, just like people. There are no God and angels in their myths and legends, and no heaven in a Christian sense of the word. They might have multiple Gods, such as the God of fire, or God of wind, God of water, etc. They are deities of the elemental.

We also believe heaven and hell too, but we dont have best picture about them. Maybe these ideas came from other religions.