Osaka - the world's easiest city to have a good time in - in just three days

Of every city I've visited in the world, nowhere has a lower bar of entry for having a good time than Osaka.You can come here with no plans, and no ability to speak Japanese and still have an awesome time.The streets are clean, there's food and music everywhere. Even on the rare occasion you get lost, that's where the fun begins anyway.For the casual Japan traveller, with three and a half days to spend in Osaka - here's how I made the most of it.READ MORE: Is it worth doing Disney World with a one-year-old?How to get to Osaka from Kansai International AirportMy flight was delayed and I arrived well after 10pm, so even though I had booked a train ticket through Klook ahead of time, I missed the last of the fast trains into town.Despite that small drama, it only took me about 50 minutes to get to my hotel on the suburban rail. One of the greatest quality of life factors about Osaka is how frequent the trains are and how widespread the network is.I just used my phone to tap on to the subway. I had pre-loaded a Suica Card - Osaka's Opal or Myki equivalent - with about $10 dollars.Navigation mistakes in Osaka aren't punishing, since another train comes every four minutes at most - signs and announcements on the trains are in English as well as Japanese.READ MORE: One reason luggage can get damaged - and it has nothing to do with baggage handlersBest place to stay in Osaka NambaJust days before my trip I booked my night's accommodation at the Candeo Hotel Namba.Good lord, what a hotel. It had all the usual features you'd expect like a breakfast buffet, and nice rooms, but what put it a cut above the rest was a spa and sauna available for free, and open overnight from 6pm till 6am.Coming back to base camp after a long day of walking and unwinding in a spa is tough to beat. A word of warning - by Australian standards, Japan is a lot more casual about nudity in the spa area, so the etiquette is to mind your own business and avoid small talk.Facilities aside, the hotel was located smack-bang in Namba, the nightlife heart of Osaka. What to do on your first night in OsakaChances are you'll probably find yourself in Dotonburi first - think Times Square but with fried Octopus Balls, a.k.a Takoyaki for sale on every corner.The main Dotonburi street is a must-visit, especially at night - you'll be blasted with neon lights, music, the sight of millions of people and the smells of the best food you've ever had.Osaka's street food is often compared to American "soul food", which I think just means it's delicious and goes well with a beer.The seafood fry-ups, sushi, and ramen were incredible and super affordable thanks to a friendly Aussie exchange rate. Pop into any of the bars off the beaten track and you'll easily discover a hidden gem like the vibrant "Top Standard Jazz Bar".One thing that really stands out about Osaka, is that every cafe, bar, and restaurant feels curated to be a nice place to hang out.Best Activities in OsakaThough it's hard to say in Osaka, there is more to life than just eating good food and enjoying cool bars, so you'll need to find some fun things to do during the day.Nearly all of my activities were booked through the Klook app using the "have fun in Kansai" package, and I never had any problems finding or getting access to the attractions.Here are my picks for some of the best that Osaka and the surrounding areas have to offer:The Sumo Hall HirakuzaDinner and a show of epic proportions. Sumo fights only take place a few times a year, so the next best thing is this Sumo exhibition night. It features famous Sumo athletes with some of the most impressive physiques in the world - One weighed in at a limber 230 kg. They'll take you through the history and techniques of Sumo before they throw down the gauntlet to the audience.Universal Studios JapanPure adrenaline is on offer here, and is easily worth spending at least a day here. You can read a full review of Universal Studios Japan here.Osaka CastleThe castle was a must-visit museum for fans of the show Shogun, or just castles and history in general.Teamlabs Botanic GardenThis is a combined effort between Osaka's botanic gardens and the people behind the endlessly Instagramable TeamLabs. You can easily lose an evening in the interactive light shows. This one gets bonus points for the most friendly guides and staff.Kobe: Mountains, Sea and Sake walking tourThis half-day walking tour was such a welcome change of pace after a few days of overstimulated fun in Osaka. After 15-minute bullet train ride to the next town of Kobe, I met up with a tour guide from Snow Monkey Resorts for a walk in Kobe's Mountain garden. The tour guide was another history buff, so gave an awesome look into Kobe's culture and history as the first city to interact with the Western world.We learned about traditional sake-making methods, spent a sunny afternoon walking around the world's biggest Sake-production district and tried Kobe beef - I'll say no more about that except I had a great nap on the train back to Osaka.Tsutenkaku Tower SlideThis attraction was in a cool spot ,so was worth a look around and some photos, the slide was fun and on the cheaper end of things to do.ShoppingI checked out the Pokemon and trading card shops - Japan was gripped by Shohei Otahni mania with the world series on. Pop culture stuff in Japan is everywhere so the Department stores in Namba can cater to that if it's what you're after.Otherwise, cosmetics are cheap and plentiful so you can bring something home as a gift.Solinawa OnsenI visited another Onsen on my way out of Osaka. Judging from all the health benefits listed on the various spas (including carbonated water, ultra-hot, and geothermal spring water) I might live to be 110 years old.Well worth an hour's visit, and the ticket comes with a free meal.If you have a spare three days on your Japan itinerary, you'd be crazy to miss out Osaka and the surrounding area.Best time to visit OsakaThe best times to visit Osaka are during spring (March to May) and autumn (September to November), offering pleasant weather and beautiful scenery.Spring is particularly popular as it is also cherry blossom season.This year, blossoms in the Osaka region are expected to bloom on March 30, with full bloom on April 6.The writer travelled as a guest of Klook.