There are a number of reasons as to why these children do not go to school. There are many cases where they cannot understand the Japanese language. In other cases they may be able to understand both Japanese and their own native language, but their level of conversation is insufficient to participate in class lessons. Bullying by native Japanese students may also contribute to their choice not to attend school. In other cases, the children have parents who both work to support the family, and the children end up being left at home alone. In these families, they spend time together late at night after their parents stop working. On their parents' day off, they go out late at night together (shopping, etc.) They pass their time at autonomous Japanese language classrooms that were built for the children of foreigners. These parents are usually blue collar workers.
Other reasons are that the parents of fushugaku children want their children to go to a school where they would use their native language. However, such schools cost between 30,000 and 50,000 yen per month, so parents cannot afford to send their children.