This iteration mark is a symbol used to omit the repetition of the same kanji.

He is learning how to write kanji using Kanji return.

It's difficult to find a list of commonly used kanji.

It's better for him not to know the truth. After all, ignorance is bliss.

He is feigning ignorance about that problem.

He knows that pain through his own experience.

I have no way of knowing what he is thinking.

He is working hard to make his abilities known to the world.

In order to understand his feelings, I had a deep conversation with him.

God only knows what he is thinking.