Hallo,
Yes, 4 to 5 day stay isn't long enough to fully experience Tokyo life. I think you need to stay at least 3 weeks here! It's the world's busiest city, so there are always so many things going on everyday.
It is a fun, crazy, and very interesting city to visit. However I would not recommend people to live here. Once you start to work and live here for years, it'll become a hell!
I'm not sure how long I'll be able to survive in Tokyo. I cannot wait to get out of this country anytime soon!
I'm like you, I only stay here for business. With my heart I know this is not the final destination of my life.
If you ever visit Tokyo again next year, then probably I'll still be here, so we can hang out. Make sure you'll stay here longer next time so you can experience a real crazy Tokyo life ;)
Meanwhile, I'm very much looking forward to having another adventure in Spain soon!
Mari