Were to translate Japanese in English...for example to translate getsuga tenshou?

Phrases used in manga and anime are not always in dictionaries.

If you read manga, and are familiar with Japanese, you can find the raw version, figure out how your wanted phrase is written in Japanese (kanji) and try online dictionaries such as dic.Yahoo.co.jp , goo.ne.jp, jisho.org, bab.la, EUdict.com, among many others to figure out each of kanji's meaning.

If not then wiki's almost always work, especially for famous stuff like Bleach.