If you want the 100 blocks quest done, you have to get the premium content :L
Also, you can upgrade your stuff if you also have bought the content in a city called "Crow's Nest". So yes, it's possible for people to upgrade items before you rescue Shigeru.
Why do so many people think Asura's hard to kill...
I instakilled him when he was trying to regenerate. 2500 damage hunters ftw :D
Also possible to kill him as assassin.
[i]*SPOILER ALERT*
Once you reach the final city village thing, where you fight Kasura, it's easy to get past the poisoner enemies, like that Naga lady and the Mistwalkers.
With the first boss, just turn away from her if she tries to stun you, and dodge her poison cloud projectiles once she's suspended in the air. After that, just hit her repeatedly.
With the Mistwalker's, it is really annoying to try to fight them. If you have a range advantage or clone ability, it's moderatly easy. If you're like, a squishy warrior or hunter though, take caution. One poison ability from them can kill you, unless you can dispel it.
Kazuro is annoying. He doesn't really have poison, but the fact is... he makes a clone of you, and he's just suspended in the air while you fight the clone. 1 v 1 combat is a frustration, but the key thing is to burst him down and to make sure you can sustain yourself, possibly with a potion or regeneration item/ability. That's all :3