I just came back from Japan and gotta say it is definitely worth a long visit. The 2 weeks would even be a tad short, but still a great opportunity. Food is not expensive so you dont “save” a lot on it in this thought experiment, but hotels, especially during sakura time right now, would be a big one. And well, just getting a chance to experience Japanese culture, especially coming from “rude western countries” is pretty great. Definitely gonna go back there.