Not sure if this is the correct place to ask. I am sure your HR in Japan will know better.
For reference my company have hired a Malaysian girl directly from KL with 0 knowledge in Japanese to do Finance.
No idea what my HR did. As far as I know, Japanese is not so important for visa.

My original purpose is to go there and study Japanese language for 6months - 1 year while trying to attend as many concert / live house, art exhibition and attending cultural event since I love their neo-modernism culture.
To be honest, I didn't really learn a lot because they taught everything formal and a lil' bit old school, the phrases I learnt and trying to converse with my Japanese friend at first felt awkward because I can't apply in real-life.
I got called "showa gaijin" because the way I speak like stuck in the 70-80's.

Yes, Japanese language is important since most of the people you will work are Japanese and their main communication solely Japanese language.
Unless you have close Japanese friend who are international-ninja (knows outside culture and fluent in English) but rare.

I met like 5-8 Malaysian who only speaks basic conversation and been living for almost 5-10 years.
Most of them working for Big Foreign Company or English Business Teacher for Business English School (ei-kaiwa)or English for Primary School Children, and of course Married to Japanese wife/husband.

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How I get my work in Japan goes like this..

One day, I felt bored after class after 1 month.

I asked my Japanese friend who are in the same industry is it possible for me to work in Japan maybe in long-term since I generally like Tokyo as 1 city and also the convenience of going everywhere without having cars.
They said is possible since I have the skills and unique experience. I only need to find the right person and everything will be fine.
So, they offered to help me, learn a few important phrases, word and structure sentences real-life and send a few agencies recommendation.

Straight 2 months after 1 month in Japan. Beside them helping me looking for vacancy or spread my name to a few agencies they know.
I apply a few agencies and commercial studio that I bookmark a few years ago when I'm in Australia. Send them an email and also post mail just to show my existence and my seriousness.

Out of 100+, I got like 20+ response to visit their office/studio just for meeting and see whether I'm fit to join with my specialty.
Majority of them have the photographer that have similar specialty with me, they're not interested to hire because afraid the job they receive can only support 1 photographer. But we still keep in touch until now.

End of Spring, before Summer season comes on my 3rd month in Japan.
While on the way to Omotesando to check out new sneakers shoe store and chocolate cafe at ura-harajuku.
I got a call back from 1 of the agencies. The President interested to meet me after one of the senior photographer hands him my portfolio. Since I'm on the way to Omotesando Station inside the train already, I ask them whether we can meet up now since I'm around the city center. They say ok..

After meet-up with the president of the agencies, with my chapalang Japanese but understandable.
He ask me a few simple question and random one.. What kind of girls I like.. Will I marry Japanese girl if I stay in Japan long-term.. haha
They hire me on the spot as part-timer since they want me to attend Japanese school for another month or 2.

2 months later, the president invited me to have a lunch with him. This time ask me some serious question.
What if they help me to apply working visa, but I'll pay for the application (which is only 4000yen that time, around RM120+).
The next day, went to immigration applied working visa and 2 weeks later got a call from immigration, brought my passport. Get a new visa and also new resident card.

3 months after living in Japan, Got a working visa and officially employed full-time.

A month later, I got appointed to do a CM for Sandisk Japan and got send to New Zealand with my Colleague Photographer for 2 weeks.
Quite memorable one out of all the gigs I get while working in Japan.

Rental will be around 40k-80k yen a month depends on location, distance to train station and also the age of the building. Oh ya, plus the size.
Elite or Prime area will be around 70k-200k yen a month.

Average of normal rental will be cost around 60k yen a month.. If you're lucky enough, 40k yen a month is like jackpot for everyone here.
I manage to get 45k yen a month, 12 mins walk to Station or 5 mins bicycle ride to Station. Neighbourhood located at the riverside between East Tokyo and West Chiba.
Perfect spot for me to have evening breeze walk once in a while...

Depends on your personal financial. Start struggling in the beginning and enjoy the progress like any other Japanese who comes from different prefecture. (Trust me, they are broke as f*ck than any foreigner who move to Japan)
Or save as many saving as you can, start plurge in the beginning and slowly control your budget financially.

I booked a share house room a month in-advanced once I decide to move to Tokyo. Sign a non-duration contract deal and pay 15k yen deposit only and 1 month rental of 50k yen a month which is include electric, water, gas and internet bills. Opposite the Share House is Aeon Supermarket, basically every evening I'll drop by there to buy fresh food and vege and cook decent meal (cost around 300-400yen) for myself every night. Metro Station just 8 mins walk, convenient as f*ck and felt like heaven for the first time.

But I have that dream/ideal place, where I always watch Japanese movie (where those lonely single guy/lady own a cool small studio house or apartment a little bit further down from the station.)
Everyweek for 2 months, I'll visit a real estate agent and tell them I'm looking for my ideal studio house/apartment and hopefully they can find 1 for me with the budget I mentioned.

On 2nd month, Those famous or well-known real estate agent cannot find the criteria I want and I took another alternative way which is go to district local estate agent (those only accept japanese customers). Give it a try with my almost perfect Japanese conversation and ask them I'm looking for a studio house/apartment, in resident housing area and 15-20mins away from any public train.
They have a few on their list, list down to 5 apartment to see. Drove me around the area and have a look at the house or apartment.

Found the one I like, which is a House Studio (attach beside another apartment but separately), 45k yen a month, 12mins walk or 5 mins cycle to Metro Station or another 20mins walk or 9 mins cycle to different Train company station, 2 blocks away from Edo River and there's a jogging track where you can jog the other opposite way to Arakawa River. Decide to go for that Studio House.

At first the landlord reject my application because they a little bit hesitate when it comes to foreigner. And then I was lucky, very lucky to meet up the landlord at the office where she pick-up some document from the estate agency. The guy who help me apply the application point at me and say I'm the guy who applied her Studio House to rent and her first impression thought I'm Japanese instead of Foreigner (look and physically). Had a small chit-chat with the landlord and the landlord decide to cancel the reject application and let me rent her Studio House to me.

I had my first own rent studio house in Japan and cheap one 45k yen a month.
The first month I need to pay is :
First month rental : 45k yen
Deposit (You'll get back 50%-75% once you move out): 30k yen
New Key Installation : 8k yen
Real Estate fees : 15k yen.
No Key Money Fees and Landlord Fees, luck again on my side.

Total is : 98000k yen to get the dream house I want. (back in 2012,  around RM3.6k)

Basic Monthly bills on my side for own place is :
4500yen for Fiber Optics Internet (Yahoo! Hikari)
500 yen - 2000 yen for Electricity.

Every 2 months :
1200yen for Gas
800yen for Water

Total Rent include bills is : 51500yen a month. Equivalent to RM515 or conversion RM1800+

Separate non-house bills is my Softbank + Iphone Bills which cost 6k yen a month. (Unlimited LTE + Calls, most Japanese use phone mail to contact with each other. Rarely SMS)

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And again, do not convert the yen to Ringgit because you earn your salary in Yen.
The right way to see the living expenses is by seeing the equivalent.

RM1 = 100yen.

While in Malaysia you cannot buy lots of stuff for RM1.
But 100yen you can get Onigiri or Bun in a local bakery shop.

I challenge myself to Survive with only 500yen a day for a month (Breakfast & Lunch).
Surprisingly, I can get lots of stuff for 500yen in a day in Tokyo.
Like 90yen of Melon Bun with 100yen Lemon CC for Breakfast. 300yen Bento for Lunch.

But in Kota Kinabalu RM5, small packet of M&M already cost RM3 or 1 Chicken Pao already cost RM4 for breakfast.

For me working here is about money and experience.  I prefer working life back home. People are much more open and "nicer' to work with.  And as you mention working as a salaryman, is not fun at all. You cannot really make real friends in the company. Its all about business.

Thought of going back, but difficult to find a job that pays what I am getting now and also the nature of my job is too specialized and not many open position in Malaysia

I always tell my friends, coming to Japan as a tourist is fine......but to stay back and work, you need to think twice!

so much truth on this....i been working in tokyo for about 5 months and i can't wait to go back to Malaysia once my project end. The salaryman life is no joke here...  

office culture is abit weird as well. Maybe we can hangout and have fun in izakaya after work but the next day in the office, they behave like a stranger n "cold" towards each other.

YES!! go jap as a tourist is fine, but if for working....for me is abit 

I think its possible? My case is an oversea assignment to the US MNC based in Japan. I am in the accounts line too. Pass my N5 but my kanji is horrible. Kinda forgotten most of it that were in N5 exam.
Now just waiting for my work permit to be completed before I hop off to Yokohama 

There was internal posting so I applied for it. Went for an interview & gotten the assignment. My advantage over the other candidates was because I know japanese & have relevant experience