It's an old company. Old throughout. They push an image of the latest technology and hide their old image. Very two-faced company. The HQ is an old school building with every floor except the first floor and 6/7th (the ones guests can see) have very poor air circulation, dingy, cramped offices, no natural light (curtains are permanently closed) and 30+ year old chairs. Air conditioning and lights are turned off in corridors to save money regardless of the risk of injuring yourself in darkness. The company doesn't care about staff. Power harassment is rife and overtime is the norm. Don't expect to have plans on evenings and weekends as you have a high chance of being told to work. Management is terrible. Almost everyone in the company has been there since graduation and new graduates who join go through the same brainwashing to think this is all normal. The only people who can understand this bizarre world of Yonex are mid-career people who have gained experience elsewhere to compare.
Also, the 5 star review here is obviously fake since Yonex doesn't allow part-time staff to work in their HQ due to secrecy ideals. The only part-time staff are those who work in the showroom in Akihabara and are your everyday sales staff you'd find in any other store.
