How can I live in Japan not having a college diploma?

Hi Martins

The options are generally:
-Visa by family (marrying someone, getting dependant from parents, grandparents, etc)
-Work Visa. In this case, a company must want to hire you
-Student visa: This is the most common. You can either pay for a Japanese school or try for a scholarship in a university.
-Short term visa: it is destined to tourists and has validity of up to three years, with the right to multiple entries and maximum stay period of 90 days.

Perhaps these articles in Portuguese may help you:

COMO MORAR NO JAPÃO SEM SER DESCENDENTE DE JAPONÊS?
(How to live in Japan without being a Japanese descendant?)
https://skdesu.com/morar-no-japao-sem-ser-descendente/

Brasileiros não-descendentes podem morar no Japão?
(Can non-descendant Brazilians live in Japan?)
http://www.aulasdejapones.com.br/como-morar-no-japao/

Also, these other topics could help you:

Best websites to find jobs and work in Japan
https://planetyze.com/en/japan/forum/japan/living-in-japan/best-websites-to-find-jobs-and-work-in-japan 

Finding a Full-Time Job as a Language Student
https://planetyze.com/en/japan/forum/japan/living-in-japan/finding-a-full-time-job-as-a-language-student 

Full time work to exchange the student visa to job visa
https://planetyze.com/en/japan/forum/japan/living-in-japan/full-time-work-to-exchange-the-student-visa-to-job-visa

Aleph, acho que esse video aqui vai te tirar todas as dúvidas!

https://www.youtube.com/watch?v=YWubb3zPv8k