How to create a Japanese name like this?

takane's right, 真子 Mako is a girl's name -- usually. But 平子真子 HIRAKO Shinji is a fictious character from the manga/anime BLEACH, who is a boy:

http://bleach.wikia.com/wiki/Shinji_Hirako

"平 hira as in 扁平足 henpeisoku (flat feet),

子 ko as in 小野妹子 Ono-no-Imoko (ancient Japanese politician),

真 shin as in 真性包茎 shinsei houkei (genuine phimosis), and

子 ji as in 辛子明太子 karashi mentaiko (red-pepper seasoned cod roe)"

is how he explains what kanji his name takes -- yes, he's such a weirdo.

So, the Asker wonders why the same character (kanji) is read in more than one ways.

The answer is, because Japanese kanji has several readings depending on the combination of characters -- for example, the kanji 平 can be read as:

- HEI, as in 平面 HEIMEN (plane surface); also read PEI in some words (like 扁平足 above), which is the classical pronunciation of HEI.

- BYOU, as in 平等 BYOUDOU (equality)

- hira, as in 平社員 hira-shain (rank-and-filer; untitled company worker)

- taira, as in 平らな taira na (flat, level)

Those readings in uppercase come from Classical Chinese (referred to as "on-yomi"), lowercase being native Japanese words ("kun-yomi").

Such is the case for pretty much every kanji. Yes, it's such a pain in the neck even for us native speakers, but that's the way it is.

Hope this clarifies it a bit.

Shinji is boys name.

but 真子like girls name.

normally read it "Mako"

　

onameimoko = ono no imoko?

he is men, however "imoko" is very old historic style name.

btw, henheisoku= henpeisoku, kamoshimentaiko= karashi mentaiko

↓あ、ブリーチのキャラ名だったんですね。

　ありがとうございます。

I have no clue what you're trying to ask.