I used to have a budgie and a cockatiel (I was manipulated into giving them away and it was the worst thing I've ever done.) that were bonded together and I feel that budgies do better if they have another friend (preferably of their own species, two females or a male and a female) with them if you are at work most of the day.
Birds, especially psittaciformes are extremely intelligent (
Birds have primate-like numbers of neurons in the forebrain) and so need a lot of mental stimulation as they can mentally ill just like humans. Toys are expensive but so are vets bills for when your pet becomes depressed and starts self-mutilating. This will give you an idea of what types of toys are available for budgies:
Parrot Toys | Buy Online, Huge Range Of Safe Fun Bird Toys. My budgie used to like toy that he could preen and chew on.
Big cages are really important, the minimum requirements for a single budgie are: 30x18x18 inches but the bigger the better.
My budgie and cockatiel shared this cage:
Voyager Open Top Parrot Cage (only because he used to slip through the bars and into her cage so he could be with her so I gave up in the end and let them share.) My parrotlet currently has this cage to himself:
Liberta Oregon Flight Bird Cage.
Time out of the cage is really important too, they need at least 4 hours a day.
Also if you do choose to get a bird be prepared to throw out all of your non-stick cookware (
Teflon and other non-stick pans kill birds | EWG), candles, incense and air fresheners. Birds have a very complicated and sensitive respiratory system (
http://www.peteducation.com/article....+1829&aid=2721) and are prone to infections.
Budgies need a varied diet of seeds, fruit and veg. I used to give him a teaspoon of this:
http://www.northernparrots.com/harri...ood-prod58115/, a sprinkle of seeds and some fruit/veggies each day. My budgie's favourite veggies were spinach, rocket and carrot. And as a treat I used to give them a pinch of these:
http://www.tesco.com/groceries/produ.../?id=274157683. Here is a good list of safe foods:
http://www.cockatielcottage.net/tablefoods.html.
Also another thing to keep in mind is that budgies can live 20-30 years.
This is all I've got for the moment - my brain is a bit frazzled at the moment - but if I think of anything else I'll write it up. I don't know how easy most of these things are to get in Japan but it may be a case of having to order from overseas.