Health Insurance not more than 6 months

I am staying in Japan for 6 months for internship and will be going back to my own country in March 2019.
My question is,

1) Do I need to pay the health insurance or not? Because some of the students staying here say it is okay not to pay for the health insurance because I live in japan for less than 1 year.

2) If I dont pay the health insurance, will there be a problem once I come back to Japan for a visit?

Yes, you should pay it.

It is both cheap and valuable. Pay the minuscule amount they will charge based on your Japanese income from the previous financial year (which would be zero).

When I did internship in Japan I had my health insurance from my country. I had already standard option for world wide coverage. Anyone visiting Japan for less than a year is encouraged to arrange an international private medical insurance or travel health insurance.

Depending which country you are coming from international insurance can be very expensive - 10,000 yen per week! Than is not a good idea. The Japan NHI is soooo much cheaper.