What do you think about them ?

Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninya``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninfa``Ninja``Ninja``Ninja``Ninqa``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``3inja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninza``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Zinja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Qinja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja
Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninja``Ninxa

Solutions :

Among all those "ninja" words, some were uncorrectly written. If you gather all the "wrong" letters, you get this : yfq3zZQx

Eight-character codes are often puzzle codes on itstoohard, you were supposed to go there : http://www.itstoohard.com/puzzle/yfq3zZQx

These were the answers to the first questions :

• Q1 Murasaki
• Q2 Yoji Shinkawa
• Q3 Yuffie Kisaragi
• Q4 Ayame & Rikimaru
• Q5 Onimusha 3
• Q6 Samanosuke Akechi
• Q7 Olga Gurlukovich
• Q8 Hamato Yoshi
• Q9 without honour
• Q10 Kawasaki
• Q11 Japan
• Q12 Japan
  All of them could be answered with different format (ex : honor/honour, Ayame & Rikimaru/Rikimaru & Ayame, etc...)

As for the second part, it mentioned a "hidden shinobi" in the previous puzzle, and the image hinted the word "source".

Previous puzzle + source, you had to check the source code of the previous itstoohard page and look for the hidden Shinobi.

It takes the form of these kanjis : 忍び ("Shinobi") they kind of strike the eye when you're looking at the html code.

I had a lot of fun creating this puzzle and I would like to thank all those who participated for their positive feedback !! it makes me want to make more.