How to acquire residence visa as a half Japanese?

Hi! My friends needs my help about getting a residence visa and he is Half Japanese, Half Filipino.

Short background, his mother and father are married (father married twice) and around 2000’s his father died. He has half older brother currently living in Japan sent a mail to the Philippines about his father’s death but seems he’s not interested on helping his half younger brother obtaining a Japanese Residence.

What are the ways he can obtain Japanaese Residency?

thanks!

by DesperateBaker4832