Work for foreigners

Hi, can foreigners just go to a Japanese company or its website stating that they have a certain certificate at a certain field and just get a job like the Japanese? or are things more complicated? if so, can they for example state they can accept a lower salary than Japanese employees (for example one-half) and get the job?
Thanks

can foreigners just go to a Japanese company or its website stating that they have a certain certificate at a certain field and just get a job like the Japanese?

No, unklike Japanese nationals, they need a visa, which, unless you stay on a spouse visa or working holiday visa or some other self-sponsored visa, has to be sponsored by your employer. Some basics:
http://www.japan-guide.com/e/e2231.html

if so, can they for example state they can accept a lower salary than Japanese employees (for example one-half) and get the job?

No, an employer who sponsors your visa is not allowed to pay a salary that is lower than the salay a Japanese would get for the same position.