Fastest &way (from Kawaguchiko to Osaka)

We�fre going to spend 1 night at Kukuna located @Fujikawaguchiko and will then be traveling to Osaka the next day.
Got suggestion to take bus to Mishima and from there to board the Nozomi or Tokaido Shinkansen to Osaka. Does it make better sense instead of returning to Tokyo for boarding the Shinkansen from there ? Any other better ways ? Your suggestions & advices will greatly appreciated.

Going through Mishima can be faster, but there is more room for error. The faster Hikari trains only stop at Mishima a few times a day, and if you miss those, then you are stuck on the much slower Kodama. If that happens, it becomes quite a bit slower than going through Tokyo.

Are you traveling on a JR pass or buying individual tickets? If it's the latter, then going through Tokyo and riding the Nozomi is just as fast as and gives more options. So I wouldn't bother with Mishima. If you have a Jr pass and have to use Hikari trains, then I would figure out when you plan to leave and use google maps to see which way is faster.

There's also the direct overnight bus.

much slower Kodama.
Actually, the Kodama service is not "much" slower - they take a little longer (not huge), but they do stop at each station. I sometimes use them and know the timetable and timing differences. Maybe in the past they were "much" slower, but not so much these days for the Tokyo to Shin-Osaka route.