Is 靜目 夏樹 a valid name in Japan? Also, I am just curious, but how do you generally check the validity of a Japanese name?
夏樹 is a natural first name, but I think 靜目 is a rare family name. This is the first time I have seen it.
As for first names, parents need to register their child's name with the government when their child is born. There are some rules when they register them. Katakana, hiragana and kanji can be used, but kanji only for ordinary use (常用漢字) and for person's name (人名用漢字) can be used. Names which lack common sense like 悪魔 are not allowed.
In the recent years, first names which we can't read correctly have been increasing which has become a problem. 当て字 (Readings that are different from correct readings) are used in them and they are called キラキラネーム.
As for family names, they are many and varied, and are mostly derived from places where they lived or their holder's job.
We generally don't use kanji and words which have ill or bad meaning for names.