SEASON 1 - The story starts with a boy named Kensei Kibo who was born into the Kibo Clan. He is the Kamishikara (A human who has a God Samurai sealed in him/her) (A god samurai is one of the samurai created by the gods with specific elements) who possess the power of the God Samurai of Thunder and Lightning. Kensei is born in to Nomi Province in Japan but the village was soon destroyed as the Midoris raided and took their land. Kensei's mother later takes him into Heimura without being caught. Fast forward 12 Years Later, Kensei participates in the Aonisaibushi assessment which is to test if you're strong enough to become an Aonisaibushi (The lowest ranking Samurai class). Unfortunately, Kensei fails the test and walks around Heimura with depression. As he keeps walking, he meets Heiwa Nashikaze (The 3rd Shōgun - The military dictator) and together they leave Heimura exploring the forests and picking up herbs.
Kensei explains how he fails the Aonisaibushi assessment and Nashikaze feels shocked as he can see potential in Kensei. Later, Nashikaze and Kensei are both ambushed by a Shinobi (Ninja) named Kazuki. Kazuki tries to persuade Kensei into becoming a Shinobi and join forces with him (Kazuki knows about Kensei being a Kamishikara while both Nashikaze and Kensei don't). Kensei refuses after a long time thinking and Nashikaze pulls out his tanto (short sword) and fights Kizan. Of course being the Shōgun, Nashikaze beats him but Kizan pulls out a clone and attacks Kensei. Kensei is unarmed so he can't really do anything but then, Nashikaze gives Kensei a Katana (A medium sword with a curve at the end) and together kill both Kazuki and Kazuki's clone. Nashikaze being impressed with Kensei changes him to an Aonisaibushi himself.
A week later, Kensei joins the Young Heimura Bushi Academy (an academy for training going Samurai form ages 12 to 15) and is amazed by everything. He accidentally bumps into someone who is only one year older than him named Maeda Keiji from the Maeda clan. Keiji explains his identity as so does Kensei but then another person arrives with pink hair which Kensei hasn't seen before. The girl introduces herself calling herself Heiwa Momoko who is the same age as Kensei. The three quickly become friends and start taking a couple of missions together. After at least a month, Kensei has gotten more experienced with the Katana as well as the YHBA, then, he meets someone else, his name is Midori Seijūro (Midori Saburo in the anime). Seijūro is a very cocky and arrogant guy and is hated by many. Another FAT ass person in the background has been noticed by Kensei and she introduces herself named Sanrota Keiko. After that, Mr. Weru announces that for the next couple of months, we will be split into teams of 4. Kensei is partnered up with Momoko, Keiko and his new rival, Seijūro. Their sensei (teacher) is a Seieibushi (The highest ranking class a Samurai can obtain) named Moyasu Tagosaku.
All together they go on their 10th mission being which of Kensei's favourite as their will be some action in this mission. Tagosaku takes them to a neighbouring village named the Iwanuri Province where the Iwan Clan lives. During their journey, Kensei and the others have to set up camp as it was night time and they were tired. They all had to take it in turns for night guard for only 2 hours each. The order is in 1. Seijūro 2. Kensei 3. Keiko and 4. Momoko. When it is Kensei's turn, he finds out that Momoko and Keiko are already awake and all together, go up on a hill looking at the night stars. During their time, Momoko spots three Bushi running away from some Bandits. As one bandit was about to attack Kensei and the others come to the rescue and save the assumed Iwanuri bushi. They later state their names as Okoto, Zusami and Kawaki. After Tagosaku wakes up, they arrive at Iwanuri and meet the Iwan Daimyō (Leader of a clan), Iwan Ingen. Both Ingen and Tagosaku have a fight as Ingen believes they are Shinobi but Tagosaku wins the fight.