pigg.ameba.jp is a 4 character word. It is a excellent domain length for people to type quickly.
Top Level Domain
pigg.ameba.jp is still good but not best as same as .com. This is designed to target a specific country or audience. Remember that you can lose some web traffic to .com version of the domain because people tend to type .com more than any TLD.
pigg is not a dictionary word but it contains dictionary words. Dictionary is most important to people because they will remember better without dictionary words. This domain is contained with pig