how to fix it
There are different opinions about the treatment of a hikikomori, and the opinions often split into a Japanese and a western point of view. Japanese experts usually suggest waiting until the hikikomori reemerges, whereas western doctors suggest dragging the hikikomori back into society, by force if necessary.

While there are a growing number of doctors and clinics specialized in helping hikikomori, many hikikomori and their parents still feel a lack of support for their problems on an institutional level and feel that society at large has been slow to react to the hikikomori crisis. In the last several years, a hikikomori support industry has sprung up in Japan, each with its own style or philosophy in treating hikikomori cases. Despite this diversity, there seem to be two general camps for treatment:

The psychological approach suggests psychological help is needed for these isolated young people, as many parents are overwhelmed with the problems of a hikikomori child whom they don’t understand. The standard psychological approach to hikikomori behavior in a youth is to treat the condition as a behavioral or mental disorder and so admit the child to a hospital ward in order to administer counseling, observation, and drug therapy using standard institutional procedures.

The socialization approach to hikikomori treatment views the problem as one of socialization rather than mental illness. Instead of clinical treatment in a hospital, the hikikomori is removed from the original environment of the home into a shared living environment and encouraged to reintegrate into social groups through daily activities with other hikikomori who are already in various states of recovery; this approach shows the person that they are not alone in their condition and appears to be successful for most cases.

Hikikomori may not find a free space to express himself as an individual because some feel Japanese culture doesn't provide such a frame. In that instance, a possible way of treatment is to encourage a Hikikomori to share social experiences outside Japan, for a short or long period.

In contrast to the approach of treatment, some may argue that the Hikikomori status is a personality type or lifestyle to be accepted, or resolved, within the respective families, as long as this choice doesn't lead to criminal or violent behaviour. Some argue that there is a tendency in societies -- especially those, like Japanese society, that emphasize conformity -- to label people who differ from the norm "pathologically ill," and urge greater concern for the wishes of the individual. (Similar issues have been raised about Asperger Syndrome and Schizoid Personality Disorder.)
In some cases a Hikikomori partially or completely recovers in time when given a free house or apartment of his own.