正
This Chinese character means correct or right.
You can watch how to write this. - (「正」の書き順（筆順）動画 - 漢字書き順辞典)
There are 2 main ways to read this, "ただしい (正しい)" or "せい".
When this is combined with other Chinese characters, this is often read as "せい".
For example, "正義 (せいぎ)" means justice.
"義 (ぎ)" means righteousness.
Japanese people sometimes use this Chinese character to count number of something.
Why? Do they love justice so much?
No. Because "正" is five strokes.
When you are counting balls, if you have written 3 "正", you're sure there are 15.
Japanese people don't love justice so much.
By Higashi-Mikawa Kyōjindō Shujin (東三河狂人堂主人)