I've been an ESL teacher for a few years working in a variety of places around the globe. Keio Academy will truly wear on your soul and break you down slowly - mentally and physically.
You have a chance of being a teacher that is like or being a teacher that is a punching bag and there is no in between. Foreign staff are thought of as dispensable and they make that known. The management likes to create drama amongst staff and will let it be known who is getting a raise and who isn't. Management also loves to get involved in employee's personal lives and you will have little privacy here. They know what you're up to in your free time and have no problem bring it up with you at work.
If you are sick - you better be on your death bed and even then they make it extremely hard to take a sick day. Prepare yourself to work weeks on end with nagging illnesses or injuries that just get worse and worse until you require multiple and costly treatments.
If you want to take your vacation days.... that's too bad. You can take them individually on set random days that they decide, but no guarantee they'll be approved and no guarantee it will be when you want to take them.
The contract states a 40 hour work week - you will work a significant amount more. 12 hour days aren't uncommon for the overworked teachers. Many times you will be required to work your lunch and not be paid and in addition you'll probably lesson plan in your free time on the weekends if you get a weekend. 6 days weeks aren't unheard of either. Be prepared to work outside schools, private school lessons, events, and camps. Be prepared to be worn down and exhausted. It will take a toll on even the healthiest of people.
The only positive side is you do get paid on time, however they will make you pay for things like keio polo shirts so you can advertise their company on your body. They'll require you to get health checks and pay for it. And, don't expect to make what you're supposed to be making. They decide based on how much they like you how much they'll pay you. Your experience doesn't matter.
If you are liked by management - and they will pick a select few to treat better than the rest to create that drama amongst staff, you can expect reasonable hours, a raise, better health insurance, and praise. But if you are the punching bag expect to be isolated amongst your staff because they're protecting themselves from becoming that person, low pay, 12 hour days without a break, and constant criticism. It will be difficult.
Ask to speak to teachers on staff if you're interviewing - multiple teachers - not just one. They hide potential teacher's information until they arrive to the academy so the teachers can't contact you to warn you about this place and they usually do not allow potential teachers to speak to current employees. This is a major red flag. Demand it. Demand to talk to multiple teacher's. Demand to talk to recent hires and get their take on it. Hell, demand to talk to employees that no longer work there. I've heard of only one teacher in a very long time of completing their entire contract and not leaving early. Teacher's run away in the middle of the night here.
Expect to be brought to the school immediately after your flights - even though you're jet lagged. Expect to possibly not have an apartment prepared for you and have to stay in a cheap motel that they will make you pay for yourself. And when you do get an apartment expect it not to be furnished for awhile. Even if they say they're working on it.
There's a high turnover rate here. I'm not talking one or two in a year - more like 10-15 people in a year and it's small academy. Teacher's and staff are in constant rotation.
Be prepared to be criticized on your appearances, on things that you can't change. if you're female not wearing enough make up or being unmarried, being too athletic, not being athletic enough. There's no end to it. Be prepared for very inappropriate comments regarding weight, if you're single, etc.
My suggestion is run. They are well known around the Nakatsu/Oita area for overworking their teachers. There are many better positions out there so please do yourself a favor and run away from this place.