Rakuten

• Job stability.
• Lots of company resources at your disposal.
• Looks good on your CV and attracts recruiters.
• Great place to put your head down, work hard, and have a long career devoid of too many ups or downs.

Depending on your team:

• Good work-life balance.
• Interesting work and a chance to learn how large systems on production work.
• Relative freedom with less or no micromanagement (depends on who your manager is).
• Good coworkers.
• Everything is in English.

• Low pay comparatively.
• Raises are low even with good appraisals.
• The environment can be chaotic, with teams working on projects that are suddenly scrapped. Teams not part of the core business can feel like start-ups, pivoting from one project to another. Different teams may work on the same thing without knowledge of each other, etc.
• There's a huge turnover of employees. You will constantly have team members or managers leave with no replacement for months or years, impacting work and morale directly.
• Currently, employees are being forced back to the office as the end of the WFH policy is near. I understand WFH is not a common benefit in old-school Japan, but in the pool of companies that hire engineers (foreign and local) in Japan, many allow extended or even permanent remote work. Rakuten will of course be compared to them and be found wanting.

There is a clash between global work culture and old-school values in the company at the moment, and Rakuten seems to be refusing to admit that the world has changed in two years.

The other companies competing for engineers in Japan are offering a more flexible work culture and better salaries. Unless you match either or both, you will keep losing employees and not be able to hire new ones of quality.

Try to retain employees. Right now, you are bleeding profusely, and this impacts remaining employees greatly as their team members and even leaders leave and are not replaced for months.

The only way to retain employees or hire replacements is with competitive salaries and competitive benefits.