Ok to answer your question, yes it is hard to become a Japanese citizen, but it is possible. The person who made the comments about relatives does not know what he is talking about. If you get married and have lived in japan for more than 5 years, are fluent in Japanese, no criminal record you can apply for Japanese citizen and, depending on if the immigrations office believe u are worthy(that's the hard part) then u can get Japanese citizen ship. The only other way u can get is if are naturalizing so u can be put up as a Japanese icon or represent japan in some other fashion, ie sports star, great doctor, owarai talent etc. Ie J.R Henderson become J.R Sakuragi and represented Japan at the 2006 FIBA world championships. Bobby Olugon, an owarai talent and comedian became a citizen because of his popularity in Japanese entertainment industry.
For UNI, if you have a degree from an overseas institution it is still credible in Japan, and entering UNI is extremely easy as u are post grad student or (daigakuinsei), therefore you do not need to take Japanese Language Proficiency Test. If u are an undergrad it is extremely difficult to enter uni in Japan as a foreigner because u must Pass the top level of the Japanese Language Proficiency Test as well as an English test. Most Japanese UNI's are happy to take on Post grads from overseas as it is seen as increasing their stature as an academic institution.
About Discrimination.. depending on the Industry you are moving into. this will determine the level of discrimination against you. For industries like English teaching at senmongakko, Juku, English schools, high schools etc there will be very little discrimination (they will more than likely choose you over a Japanese native how is a qualified English teacher) and all u need is a tertiary education and be a native english speaker to do this (for uni u must be a qualified English professor with alot of experience and/or have made 2 recognized publications in the field (requirement of MOST Japanese higher education facilities)) .
However in most other industries especial big business you will be discriminated against while searching and more than likely within the company unless it is an international company such as Nestle, Sony, etc where u are working in Japan but dealing with the international market side of the business. If you have a degree from a Japanese institution then there will be less discrimination, but still more than you would like.
If you or anyone else needs any answers or has any questions about Japanese culture, moving to Japan, working in Japan etc, please PM me and i will answer your questions