Should I take this risk? If so, how can I persuade my parents?

Are any of the teachers native Japanese speakers? I would go with the teacher who is.
Have you looked at the practice tests? The current Level 5 (used to be level 4) is “easy” and can be passed with basic study. The next one up is much harder. I speak Japanese and worked in a Japanese office for a number of years. I read and write basic stuff and can use a Japanese word processor. I can get around anywhere and talk to anyone. And I only passed the old level 3 test (when there were only 4 levels). I think that is the current Level 4 test. How far along are you? How far do you plan to go?

@LuckyGuy The school wants Level 4. And I think I’m at somewhere between level 5 and 4. If it wasn’t for my school’s requirement I would just continue studying in the center. I want to learn for knowledge, not for any certificate. And that teacher I talked about is a Vietnamese.

By the way I didn’t know you are good at Japanese :)

Bikkurishita? Mochiron, dekimasu yo.

Does this mean you have already passed the new level 5 and you are going for the new level 4? That is quite an accomplishment.
I have a word of warning about teacher selection. You know there are many levels of formality (te) My first teacher in Japan was a well educated, early 20’s Japanese female. I was a 40 something man. After taking lessons for about 6 months one of the Japanese guys in the office said, and I quote: “You are taking lessons from a 23 year old woman from Tokyo.” What?!?!? I was at a restaurant with him, wanted water and called it “ohiya” instead of “mizu”. He said I was talking like young woman. I should fire her and get either and old, strong woman or a man about my age as a teacher. I had no idea words were that specific and there were accents..
Just as native English speakers can tell if a speaker is from New York, or Texas, or Louisiana or Georgia, Japanese speakers can tell. You want to speak NHK style. Make sure to mention it to your teacher and see if she knows what you are talking about.

Good luck.
By the way, I knew you were good with languages. but I had no idea you were that good! The 3 languages you speak don’t “map” into each other like English, French, German, Spanish, etc. All the characters and sentence structures are different. Wow!

You can’t tell from the inflections but I was using a little slang. I did not use the “ka” after “bikkurishta” . My voice would inflect up so you know it was a question and since I was saying it to you, you can infer that I was asking you if you were surprised. Also note the use of Dekiru (to do) instead of hanasu or shaberu (speak). I don’t know if it was regional or not but that is how the guys spoke in the office. “Nihongo dekiru?” Not the full sentence: “Nihongo wo hanasemasu ka?”
NHK uses full sentences but when you listen to casual speakers you will hear the difference.
My second teacher was an older woman who agreed to always speak to me like a man. She was very strict. That was good. .

@LuckyGuy thanks for the tip. I will tell her that. But how can I persuade my parents that I want to learn with her?

And you got me confused for a while without that “ka” :p Thanks for the lesson.

You would not have been confused if you heard my voice. The ending used to drive me crazy. The engineers (middle aged men 40–60 years old) would talk in long monotone sentences and then right at the end say “da” which means it is an absolute statement or “ka” which means they were asking me a question or “desho” which means “maybe”. Often I would be concentrating so hard on the details and meaning of the sentence and not know whether they were asking a question or stating the fact. I like the way English lets you know right away in the beginning of the senctece.if you are looking at a question “What, who, how…” and then ends in a ”?” . Much easier and less confusing.

I’m not sure if you know other languages but if you have time check out Korean Hangul. the character set is so powerful you can perfectly pronounce almost every language. That is why most native Koreans who speak English pronounce words much better than most native Japanese. Katakana and hiragana are too limiting. Hangul covers everything. It even has room for expansion! Genius.

Ask both teachers where they learned Japanese. Go with the better, more strict teacher.

I agree with @LuckyGuy. Make sure you get an instructor who has lived in Japan and/or has native-like pronunciation and will teach you the CORRECT endings/emphatic expression to end your sentences. There are different ways expressions are used according to gender, role (superior/junior) and more.

I made it to ni-kyu (Level 2) while I lived in Japan..and had I made the effort probably could have done Level 1…but it didn’t mean anything to any of my employers—so I didn’t work at it.

What they cared about was my fluency, pronunciation (which was native-like back then, or so I’m told) and my ability to explain things in technical and business/polite Japanese that mattered more than how many Kanji I knew. (And I could read books and newspapers and understand anything on TV..so I didn’t feel like spending more time on studying when I was comfortable where I was at…)

@geeky_mama Sugoi! Ni-kyu!!! Each test is exponentially more difficult. You must be very good!
As an engineer I could explain anything. I was given a pass if I did not use the correct form. All the other engineers could understand me and I could understand them. Level 2 was way beyond what I needed. I humbly bow to your expertise.

@geeky_mama I may ask you to teach me ~

I don’t understand why you want to convince your parents. You have doubts yourself. Why don’t you just consult with your parents… discuss all pros and cons. Then arrive at a decision together.

@LuckyGuy – Meh, I just got lucky and started young. Immersion is the way to go, ne?
@Mimishu1995 – I wish I had the time, but I’m at a point in my career where I couldn’t even spare time to teach my own three kids Japanese sufficiently, much less a lovely young person remotely. ;)

@geeky_mama You must admit she would be a great student. Atamagaii !