Is there such thing as an absoultion in buddism or shinto?

you know, forgiveness for doing bad or something?

Not as far as I know.

Yeah, sure. All religions are the same; just spiritual mambo jumbo.

No there is not. The goal of both is to escape the merciless reincarnation cycle in which wrong acts build up bad "karma" for which one suffers for in each successive life. If a person can build up enough so-called good karma, he or she can escape the relentless cycle and enter "Nirvana" where existence as an individual entity continues no longer. In Nirvana one simply disperses into the "energies and forces of the universe." The belief systems are rather senseless and here are some reasons why: For one, it is stated that there is no immortality of the soul. How could a being go from reincarnated life to reincarnated life without that existence? Humanity should be getting better and better as people should be learning from their bad karma. The population of the earth should be going down as more and more people should be escaping the cycle and entering Nirvana.
Actually Christianity is the only world religion where unmerited forgiveness is offered. All others require some sort of appeasement of a god, gods, or forces like karma

Shintoists believe that everything and everyone starts out clean and pure but pick up "spiritual dirt" along the way from negative thoughts, actions, or contact with unclean substances (such as blood). Shinto rituals are designed to remove the contamination and restore the original clean state.

Absolution in Western religions starts out with the assumption that everything starts out bad. This lays a guilt trip on the followers and makes it easier for the leaders to get the power and wealth they desire.