Kimimaro did not need to learn the Sun Seal because Natsuki's bloodline was already within his body, allowing him to directly draw upon the Sage Core.
That was one of the benefits of Natsuki's bloodline.
For other Uchiha Clan Members, they might have to think of other methods.
Once the Sage Core was complete, they could try some other approaches.
As Natsuki began absorbing Natural Energy, he no longer had to stand there constantly making Sage Chakra.
With his current strength, he no longer needed to sit around nervously waiting for the Sage Core to be completed.
At his current rate of absorption, if he did not go to the Rainbow Crystal Wall, he should be able to make another one in fifteen days.
Natsuki was in no hurry and had no particular intention of going to the Rainbow Crystal Wall.
He turned to look at Haku beside him.
Haku had changed into a pale blue long dress today and stood quietly to one side.
She could sense a large amount of Natural Energy being drawn into Kimimaro's body of its own accord.
That was far faster than her own cultivation.
Natsuki consoled her. "Haku, your body cannot adapt to a Sage Core, but your starting point is higher than Kimimaro's. There's no need to rush for now."
"I know, Lord Natsuki."
Haku shook her head with a smile, unconcerned that her cultivation was progressing more slowly.
Naturally, Natsuki would not play favorites.
"Everyone has a different method of cultivation. If you cultivate as you are now, your gains will be relatively low."
"Orochimaru and I have thought of another method, but we won't discuss that today."
"We've all just been revived. Let's go see our friends first."
Haku suggested, "All right, Lord Natsuki. Why don't we go see Sister