HIKO SEIJURO
The 13th master of the Hiten Mitsurugi School who is the master and trainor of Kenshin Himura. He's intelligent and physically strong. He believes in the Hiten Mitsurugi principles and believed that the power should be used to a certain extent. He strongly disagreed when Kenshin decided to join the Bakumatsu because he knew that it would make a difference and Kenshin must take sides. He decided to stay neutral. Kenshin disobeyed him and joined the group. The two didn't part well but Hiko met Kenshin again when he was asking his master to teach him the last secret technique in the Hiten Mitsurugi to defeat Shishio Makoto.
At first he didn't want to teach Kenshin the technique because he thought that Kenshin didn't change but was later convinced when he saw Kaoru and the others. They told him that Kenshin changed a lot by deciding not to kill anymore but instead help people through the use of his reverse-edged sword. He decided to teach Kenshin the Ama Kakeru Ryuu No Hirameki ( this is a deadly technique where the swordsman attacks you once but he will be able to hit nine parts of your body ). Kenshin went off to fight Shishio using this technique and of course, Kenshin wins.
SAITOU HAJIME
Also one of Kenshin's adversaries. He's a very skilled swordsman also and served as the third captain of Shinsengumi unit during the Bakumatsu Douran. The Ishinshishi, the group were Kenshin belongs, were enemies. When Saitou and Kenshin fights, they always end up with a tie. Because of his skill, when the Meiji era was founded, they approached Saitou and asked him to work as a police captain. He accepted the offer and worked under the name Fujita Goru. He continued to serve as a police captain for many years and married a woman named Tokio.
When Shishio Makoto started to show up again, the higher officials asked Saitou to look for Batousai. It was easy for him to look for Kenshin. The two ended up in a deadly fight and both seemed to be transported back to their assassin-bloodthirsty selves. They ended up in a tie again because they were stopped by one of the four men who paved way for the Meiji era.
Kenshin and Saitou became allies accompanied by Sanosuke went off to battle Shishio and his Jupon Gatana. They were able to defeat them in the end. But during their escape from the burning fortress, Saitou decided to stay on the bridge and it crushed. Making Kenshin and Sanosuke think that he's dead already. He appeared again when Kenshin was going to fight Yukishiro Enishi.