Yuhara studied the Fourth Hokage's mission records, thereby verifying a few things. In theory, these were all classified documents that ordinary ninja had no right to view. However, as long as Kushina Uzumaki said it was allowed, there was nothing that couldn't be done.
The mission Yuhara wanted to investigate had actually involved Kakashi as well. He still remembered how young Kakashi had been that year—and that Kakashi had even still possessed both eyes. However, Yuhara had no way to ask Kakashi directly, so he had come up with a way to examine the Fourth Hokage's mission records.
The timing of that mission was easy to determine. Kakashi had already become a jonin but had not yet obtained the Sharingan, so a rough time frame was quickly narrowed down.
Once the general time frame had been determined, all that remained was to follow the clues. Yuhara soon found the mission record.
"We've got it!"
Now that everything had been confirmed, Yuhara could begin carrying out his plan. During the following period, he devoted himself to developing a new technique. Whether it was Living Corpse Reincarnation or the Eight Branches Technique, analyzing such advanced Forbidden Techniques was extraordinarily difficult. However, what Yuhara had obtained was not merely the techniques themselves; it also included a complete set of analysis methods... It was like a reading-comprehension test where the original author's creative process had been written beside the questions. Under such circumstances, he could study them very quickly.
This gave Yuhara a suspicion. He felt that the various Forbidden Technique scrolls in Konoha might have been deliberately recorded in obscure and abstruse language. Without enough insight, one simply couldn't understand them. Since they were Forbidden Techniques, they naturally needed an appropriate barrier to learning. If no barrier existed, then one could simply be