Opal is a compiler convert from Ruby to JavaScript. JavaScript has async/await syntax for asynchronous processing. But Opal hasn't implemented it yet. The Opal community had been discussed mapping Fiber semantics to JavaScript async/await. The conclusion was it is impossible to map coroutine such as Fiber because async/await is just a syntax sugar that expresses nested callbacks into flat statements. I'm going to talk about the idea I'm trying to incorporate easy-to-use asynchronous processing into Opal.