Staying in Shin-Osaka Backpacker's Hostel was a great experience. The place is perfect for backpackers; a kitchen, a small living room and a restroom are shared. We had a traditional room with futons. It was clean and nice, just like the common areas. The keeper was very helpful and there was a grocery store near the hostel. Two minorities were thin walls (everything, including noise of the planes can be heard) and location. The place is quite far away from the city centre but luckily there is a subway station nearby. It takes about 15 min to get to Namba station where all the central places are located.
We had to find a place on the very night of our stay since we missed the shinkansen to go back to Tokyo! This tiny hostel is kinda far from Shin-Osaka Station, especially with all the luggage we had to carry, but we were warmly welcomed. It was a bit like a maze inside, which I personally liked (it had a lot of character and our stop there made for a fun bit of adventure to tell!). We slept soundly: the place was very clean, the shower's water was hot, the room was even kinda spacious for japanese accomodation standards! And, most important of all... the beds were extra comfy! Thank you!
The house is in a kind of traditional Japanese style with sliding doors, a nice high-tech toilet, and comfortable showers. There is also a kitchen and a living room that can be during the day. Kei, the host, is always available if you need him. He was extremely accommodating. On our way to his place, we had lost our phone on the subway. He immediately took down a detailed account of what happened and advised us on what to do. The next day, he made a call to the subway station on our behalf (we don't speak Japanese) and over the course of the next couple days, gave us continuous updates on the situation. He finally tracked down the phone to a lost and found office in a particular metro station in the city where we went and picked it up! We thought we had lost it for good! Would definitely stay here again, no question.