I started Japanese at Monash, with no prior study. Yes, like me, you can walk into level one Japanese with no prior knowledge, because it's taught from scratch. The speed at which it is taught is pretty fast. As IntoTheNewWorld said, first year beginner Japanese (levels 1 and 2) are about equivalent to years 7 - 10 in high school, while second year (levels 3 and 4) is high school VCE and a bit beyond (mostly "beyond" in terms of kanji... they teach fk all kanji in high school).
I've done two years of Jap units at Monash (levels 1, 2, 3 and 4 Japanese), and I'm off to Japan this year on student exchange for 12 months.
Oh: when I talk about levels... I mean... uh... each semester you take a "level" unit... so... if you take a language all year (both semesters), you will take two "levels" in that year... eg. levels 1 & 2, levels 3 & 4, levels 9 & 10... odd-numbered levels are offered first semester, even-numbered levels are offered second semester. [If I didn't explain that properly, just think of it like VCE levels... you take like... physics 1 & 2 in year 11, and physics 3 & 4 in year 12... it's the same deal - two levels in one year; one for each semester.]
Uh... Japanese, hard? I have a talent for languages <apparently>, so my experiences may not be the best yard stick. But you say you really enjoy learning languages. If this is true, then you'll love learning Japanese, methinks. In first year, you get to play games in class, like you're back in primary school, ha ha. Also, it's really rewarding to see how far you've come in such a short period of time. Overall, if you put the extra effort in, you'll reap some truly wonderful rewards... fyi: languages, generally speaking, require a few extra hours of study each week compared to your other subjects.
This is the online resources related to the textbook and workbook used for first year Japanese at both Monash and UoM:
http://highered.mcgraw-hill.com/sites/0072408154/student_view0/getting_started/#http://highered.mcgraw-hill.com/sites/dl/free/0072408154/332931/tohsaku3e_im_ch04.pdfA thread that may be useful for you to read through:
http://vce.atarnotes.com/forum/index.php/topic,16023.msg167955.html#msg167955