At 6:02 am on Tuesday, I was suddenly woken by my phone vibrating rapidly. Weak sunlight filtered through the curtains. I didn't immediately realize what was happening, but a siren was wailing and my first thought was that an earthquake had occurred. Small quakes occur constantly in this area.

However, when I looked at my phone, I saw that the Democratic People's Republic of Korea had launched a missile and it was heading for northern Japan.

A missile? I was shocked. I quickly packed my bag with my laptop, my research materials and credentials, such as my ID card. Running from my wooden apartment, I arrived at my boyfriend's apartment a few minutes later. When we turned on the television, we saw that all the channels were running the same story with details of how to evacuate and stay safe.

The alarm wailed constantly, warning people to find safe places to hide from the missile. "If you see an unidentified flying object, please take a photo immediately and pass it on to the police," the TV broadcasts repeated. At around 6:13 am, the missile passed over Hokkaido and landed in the Sea of Japan.

The tension eased, but the incident made me review my stay in Japan. The thing that most worries me is strangers entering my apartment. I've lived on my own since I came to study here in September last year. I've never been frightened, but I always lock the door when I am at home.

I think most parts of Japan are pretty safe; some of my friends don't even lock the door of their apartment when they go out. I own a bicycle, which I use to travel to school and to buy groceries. Sometimes I have forgotten to lock it, but that hasn't made a difference because it has never been stolen.

I have heard of students going missing overseas, and I keep track of the terrible stories. However, I don't worry about that too much, I just pay great attention when meeting strangers.

Zhang Yutong spoke with Xin Wen.

Zhang Yutong, a Chinese student at Tsukuba University in northern Ibaraki prefecture, east of Tokyo.