There are many brands of diapers in Japan, but not all of them are good at what they do. Some of them are also too expensive for what they do. Here’s a list of diapers that have worked or have not worked for my family.
Pampers
Pampers sells premium and basic lines in Japan, similar to what they do in the US. At Amazon Japan, the diapers are often discounted under regular cash-back programs, but they are terrible diapers for newborns. There were often poo and pee-related overflows or spillages. We aren’t sure about the cause, but these diapers are not recommended.
Merries
Merries is a more premium brand of diaper, although there are discounts at certain times at Amazon. Their diapers are comfortable and are easy to put on and take off, and so are recommended. They do not make a big size, for 12-17 kg babies, and they are expensive, so stock up on them when they are on a discount.
Moony diapers are a reasonable choice of diaper. They are absorbent and comfortable, although they might be the cause of a rash for our baby. It’s hard to prove, and normally they work fine. They also have a distinctive fundoshi-style shape and come in sizes from newborn to big. They are recommended for their price and utility.
As our baby grew larger, we figured he could use cheaper, less-absorbent diapers. The Aeon store brand rates itself at 10 hours of absorption, versus the 12 of other regular brands, but it has been effective for overnight uses as well. The side-ripping stitches are much harder to rip than other brands, but the fit is more loose, which may or may not be good for your baby (it is better for ours). At about 18 yen per diaper, it is a pretty economical choice and is recommended to try.
Goo.N is a premium brand, with a price to match. We haven’t tried it, but it’s probably expensive for a reason.
Mamy Poko is made by the Moony makers, but is a lower-cost brand. We haven’t tried it. You can read more about them
here.