Travel Tourist waiver plane ticket question

Greetings all,
I've been looking for an answer to my question for quite some time now and I was hoping any of you would know the answer. My girlfriend is studying in Japan and I'm planning to stay with her for the next five months. My plan is to leave the country within the first three months and reenter again (I've read a lot about this and in most cases this is not a problem, right?). Now my question is: How should I buy my tickets? Should I by a return ticket that goes back to the Netherlands after 5 months and a return from japan to some country near it in between? I'm not sure if immigration can see if my return ticket to the Netherlands is going to be 5 months later.
Thank you so much in advance!

There was a thread on this topic not too long ago. Actually I think there are a few threads on this.

There is no definitive answer to your question, and your entry into Japan is at the discretion of the immigration officer who looks at your passport as you enter the country.

Leaving the country and coming back to "renew" the three-month landing permission is a very old trick. In fact it is now almost a cliche. I wouldn't assume that it is not a problem. I would assume it is your primary problem.

If you have an itinerary that brings you to Japan for 3 months, then on to another country, and then back through Japan, I think your chances of doing as you plan are increased. By itinerary I mean not only plane tickets, but activities and lodgings, internal travel, and finances to support the trip. Note that immigration isn't obliged to let you enter, even with such a plan.

If you come with a vague plan to stay a while, and then leave the country and return with another vague plan, it looks suspicious.

This is a common topic on Japanese forums. The capriciousness of Japanese immigration prohibits any of us from giving you a clear answer. Every case is unique. Some people leave Japan for the weekend and then have no problem coming back. Other people have been grilled at immigration only to be turned away. My gut feeling is that genuine travelers with a plan to visit the various Japanese tourist sites are treated with generosity.

Agree with the above. Leaving Japan and then returning very soon is waving a red flag in the face of Immigration. Expect to be grilled at the very least. You could be let in without too much fuss, or you could be denied re-entry. Very hazardous to think you will just sail through though.