If you want to be there, take the subway to Mora station, not Gunam! Go out of the station by exit 3, then go straight about 10mins, passing by two bus stops, and you will see a parking space at your left side, that means you already missed the alley. Go back a little bit and go into the alley till almost the end, and you can see the hostel at your right side. The rooms are above 2nd floor, but if can't see staff behind the desk,go down to the basement and you can see Mr. Kim there.
We booked this guesthouse from the Busan airport less than 1 hour before we arrived and they were ready to welcome us! We didn't know Busan well, but Mr. Kim was extremely welcoming and helpful.
The room was good. Two double beds with a hot shower, shower shoes, and a heater. The guesthouse provides free rice, bread, jam, and instant noodles, which we loved. The Wifi was fast and the facilities were clean.
Mr. Kim was extremely kind and welcoming to us. On our first day we asked him which way to walk to have dinner. He gave us directions (although his English isn't great, it's enough to get the point across), but then came back a minute later and offered to drive us to a more downtown area as he was heading out to buy groceries. We were shocked and gladly accepted! They provide free coffee and a nice space to hang out and/or be productive both in the basement and on the roof.
I highly recommend!