If you travel in Osaka and need to keep your baggage somewhere for a while, you may look for lockers. But if the lockers are all full? Normally, there is no cloak room at stations.
But don’t worry! Some places have baggage storage center near station.
For example, at Namba Station, you can go to “Hands-Free Center”. They keep your baggage for 1day. The minimum cost is 500yen.