I stayed for a little over a week in Osaka. Hiro's Guest House is where I ended up spending my nights, since I wanted cheap accommodation, and it ended up being a fantastic decision. This is the place you pick if you are not only just looking for a place to check-in and spend the night, but you also want a genuine experience that you don't get often while traveling: seeing the bustling local hotspot of restaurants and shops that is Korea Town, knowing where all of the best ramen, onsen, yakitori, okonomiyaki, bbq and more are around the neighborhood in walking distance, and the best of all, a friend who is happy to share all of this.
The place is located a 15 min walk from Tsuruhashi station, It's very easy to find and the station leads directly to the subway and the local JR Osaka Loop line, which makes it all the more easier for JR Rail Pass holders. You could even take the 40 min walk to the popular Namba area of Osaka. The dormitory rooms are comfortable and equipped with curtains, and there's a tatami styled room on the third floor. You can do laundry, there's a full kitchenette for all of your culinary needs, a shared fridge, and all rooms have AC. Unlike some guest houses, this place has no curfew due to the automated password lock, so you just have to be mindful of the other guests. The downstairs lobby area is perfect for hanging out or having a drink even when the host is out. The humble nature of the area will most likely make it that you might have the entire dormitory to yourself as well.
However, the focus isn't all the tangible facts. What this place offers is something much more precious. The Guest House is run solely by a humble man named Hiro. He speaks English, Korean, and Japanese well so you don't have to worry about communication. He is what would make your journey into Osaka whole. He has folders with all the local transport detailed out, a whiteboard of the nearby area around Korea Town with all of the good local restaurants highlighted with their operating hours on top of Hiro's recommendations (and cool tidbits from guests around the world), you can talk to him about your plans and he could tell you his two cents about what to do, but best of all, if you can make it back before his closing hour, you can have a nice evening talk and maybe even share a few drinks with him. I've only known him for a short while, but it's enough to make you feel that you are both friends and that you belong.
If you pick this place, you won't be staying at a Guest House. You'll be staying over at Hiro's, as a welcome guest and friend.