What kind of Visa is required to work in Academia in Japan?
This might help or this. Here is the crux of the information:

The period of stay is quoted as 3 years/1 year with the following documents needed:

Passport
One visa application form (nationals of Russia or NIS countries need to submit two visa application forms)
One photograph (nationals of Russia or NIS countries need to submit two photographs)
Certificate of Eligibility (Note) - the original and one copy


This visa applied for Long-term stay for the following occupations:

Working visa: professor, artist, religious activities, journalist, investor/business manager, legal/accounting services, medical services, researcher, instructor, engineer, specialist in humanities/International Services

The algorithm for obtaining the visa is given on the first link I added.