Monday night, at around 3:45, I woke up. It felt as if something had kicked my bed (remember that I sleep on the floor) and I thought I had heard a noise as well. Nothing else happened, so I only took a look at my alarm clock and went to sleep again.
Tuesday morning however, I thought, well … actually … it could have been … So I checked the web page of the Japan Meteorological Agency, and indeed – the night before I had experienced my first earthquake during this stay in Japan! 
The details are as follows and can be found on this page: It was a small earthquake, of magnitude only 2.5 at its epicentre, which was around 10 km underground and about 22 km southwest of Ebisus’s.
Only one of my housemates felt it also. He said it was very subtle, and he heard the noise as well. He even said he expected something to happen because all the crickets suddenly went quiet…
It was a very interesting experience as it was so different from the other earthquakes I have witnessed. The bump and the noise were all – not even the lamp was shaking, but admittedly it was hard to see anything in the darkness. It was very short and only a singular occurrence, and as I said I went back to sleep immediately.
I am seriously considering to keep tally how many earthquakes I am experiencing – the ones I can feel at least. This one would be # 3 in total.