Hi, i am looking for a torrent site in which i can download japanese tv series and movies but i am unable to find a decent one

Avistaz (you need to wait until it has open registration, though, since it's a private tracker)

Nyaa

Try looking around d-addicts forums. Torrents are not allowed there but you can find information on what's available at the moment, such as private trackers and how they work.

Can't find any good website to watch Korean dramas. Please let me know a good website to download k-drama.

dramacool, kissasian,.. - tthere are many of them, so google for exact address which contain drama you want to watch.