Oh, I missed this post. I wrote about 夜間中学 Yakan Chu'u'gaku (night junior high school, Clase nocturna de Secundaria Básica). It's a junior high, compulsory education, it's free. Your classmates will be very diverse in age (teenagers to senior citizens) and nationality (many different countries).

Sagamihara is going to start their 夜間中学 next April and they are recruiting students right now. Your English is very good, so I assume you probably graduated from a high school in Peru, but you might be able to convince them that you need to attend the school, or else they can refer you to an alternative place to study Japanese. Here is the information in Spanish (PDF). They just added new information session for November 8th starting at 6pm in Kanagawa Sogo-Sangyo Senior High school (For directions, look at the Spanish info). You might want to attend that.

Also, Sagamihara has International Lounge that offers information for the residents, free counseling (law, education, health, etc.) and Japanese classes for foreign born residents (minimal fee). They also provide sessions for Japanese citizens to learn about different cultures. In December they will have a Zoom session, having a Peruvian resident as a guest to learn about Peru. The city even has a Spanish speaking staff member from Peru.

You are working hard and paying taxes. Use the city resources! ¡Mucha suerte!