I was told by one of my teachers back in my undergraduate days about twenty years ago that for me to master Japanese it would take me 700 hours of class time.
The number now seems to be 2,200 hours.
Japanese is a language notoriously difficult to learn for native English speakers because of their linguistic differences.
To start with, Japanese has three writing scripts – hiragana, katakana and kanji. Hiragana and katakana are syllabic scripts with, in general, one unit representing one fixed sound where most units are consonant-vowel pairs. Kanji are logograms with each unit representing a word (meaning) but not its pronunciation. Most people know kanji as Chinese characters.
English, in contrast, is based on an alphabetic script where each unit is a representation of a sound be it consonant or vowel. Each letter may represent more than one sound (examples: ‘c’, ‘g’, ‘a’, ‘e’, ‘i’, ‘o’ and ‘u’) and sometimes conbinations represent a single sound (examples: ‘ch’, ‘sh’, and ‘th’).