Sengoku no Mikazuki

Sengoku no Mikazuki (戦国の三日月, Crescent Moon of the Warring States) was one of the first stories by Nobuhiro Watsuki , creator of Rurouni Kenshin and Buso Renkin.  It was included as an extra chapter in an early volume of Rurouni Kenshin, and alongside the original pilot "Swordsman Romantic Story", it's pretty much a blueprint for the story itself. There's also a 2021 voice comic, with Shuichi Ikeda and Kotomi Ohtsuka as the leads Hiko Seijuuro and Isshinta.

A barely teenaged boy from the Sengoku Era, the shy and cowardly Isshinta, has been taken away from his humble village and the girl he loves, Natsu, to fight in the bloody conflict between the Kitakata and Nagumo lands.  Terrified after seeing so much slaughter and death, he tries to run away but is almost caught by the Nagumo warriors, and then a Master Swordsman steps in. The man's name is Hiko Seijuurou and he's the mightiest warrior of the Kitakata realm; after Nagumo broke their peace treaty and attacked, he's been fighting nonstop to take down as many as he can with him.

Isshinta finds himself kinda tagging along with Hiko, despite his sort-of ally's aloof and rough behavior. As they get to know one another a bit better in different ways, Isshinta realizes that Hiko's heart has been deeply shattered after having failed to the lord of Kitakata and especially his lord's daughter, the princess of the land... also named Natsu. So despite his fears and how Hiko tells him to leave, Isshinta decides to stick around him and see what will happen...

Tropes used in Sengoku no Mikazuki include:

• Altar Diplomacy - Arranged Marriage: Before the war began, Kitakata and Nagumo had made a peace treaty and one of the deals in it included marrying off Princess Natsu, the daughter of the Kitakata Lord, to the Lord of Nagumo, Iwano. But he broke the treaty, had the whole Kitakata clan killed save for poor Natsu, and re-started the hostilities...
• Badass and Child Duo: Hiko and Isshinta, though Isshinta is a bit older than the standard.
• Badass Cape: Hiko, of course.
• Bad Dreams: It's through one of these that Hiko and Princess Natsu's Star-Crossed Lovers bond is presented to the audience.
• Benevolent Boss: The Lord of Kitakata was a very kind and just Reasonable Authority Figure. Logically, when he died everything went to Hell.
• Bodyguard Crush: Princess Natsu, to Hiko. And he reciprocates. She even begged him to run away with her before the Nagumo invasion, but Hiko refused out of Undying Loyalty to her father. Then her family was massacred, she was taken prisoner, and in the present Hiko can't forgive himself.
• Broken Hero - Heartbroken Badass: Holy shit, Hiko.
• Childhood Friend Romance: Isshinta and his Natsu, two teenagers from a small village in the Kitakata lands.
• Death Seeker: HIKO, holy crap.
• Decoy Protagonist: The main character is Isshinta, rather than Hiko.
• Downer Beginning: It starts with Hiko massacring many Nagumo warriors and demanding that they come for him. Cut to Isshinta freaking out and trying to run away.
• Dual Wield: Hiko has a wakizashi and a tachi.
• Dude Looks Like a Lady: As the image shows, this particular Hiko Seijuurou (apparently the founder of the Hiko legacy) was one Hell of a Pretty Boy. Village!Natsu ends up hanging a beautifully hilarious lampshade on it at the very end, when she meets him and the newly released Princess Natsu and thinks Hiko is a pretty woman too.
• Earn Your Happy Ending: And earn it, they did.
• Expy: Inverted, the reader can see many of the basis for the Rurouni Kenshin characters they know and love in the charas of this manga:
  • The first Seijuuro Hiko has some traces of the one from RK, but with Kenshin's girlish beauty and a more fatalistic disposition.
  • Isshinta is clearly a more shy, scaredy cat Yahiko.
  • Village!Natsu is a longer-haired Tsubame, with Kaoru's Tsundere personality.
  • Princess Natsu is a frailer, gentler Kaoru.
• Hero Worshipper: Isshinta admired Hiko very much and was pretty much starry-eyed when he pulled a Big Damn Heroes to save him. Little did he know...
• Insecure Love Interest: Hiko believes that he has no right to be loved by Natsu, not after having failed so badly to her clan and the Kitakata lands.
• The Lady's Favour: Village!Natsu gave Isshinta a good-luck charm, which he carries around and cherishes.
• The Load: Since Isshinta has next to no swordmanship skills, he at first hinders Hiko rather than help. But he later becomes Hiko's extremely important emotional support.
• Motherly Side Plait: Despite not being a mom, Village!Natsu sports this hairstyle. She lives to the end, however.
• My Girl Back Home: Village!Natsu is this for Isshinta.
• Naive Newcomer: Poor Isshinta is clearly outta his element in the middle of the Nagumo/Kitakata war.
• Name's the Same: The Princess of the Kitakata land and Isshinta's sweetheart are both named Natsu. It's a bit of a plot point, even: Hiko only begins warming up to Isshinta when they find out about it.
• Never Bring a Knife to A Gun Fight: When Iwano comes into the battlefield, he brings as goddamn musket and almost kills Hiko. Hiko proceeds to subvert the trope, however: he renders the gun temporarily useless by throwing his wakizashi into the barrel, then kills Iwano with his tachi.
• Plucky Girl: Isshinta's Natsu is a fiery and loud young lady.
• Rousing Speech: Isshinta gives a heartfelt, tearful one to Hiko, begging him to go against Iwano and free Kitakata from him. And later, when Isshinta returns to help Hiko against Iwano and his musket, he gives him another about living and fighting for their beloveds.
• Shoo the Dog: Attempted by Hiko several times, in an attempt to make sure that Isshinta won't be killed. It utterly, completely fails: Isshinta may be a scaredy cat, but his loyalty is over 9000.
• Smug Snake: Iwano
• Star-Crossed Lovers: Hiko and his Natsu, separated by their social status (she's the Princess of the land, he's a simple kendo instructor and samurai) and by the fake treaty that included arranging her marriage to Lord Iwano. But they do get their happy ending.
• Tender Tears :The kind and shy Princess Natsu tends to get teary-eyed easily, and Hiko sees it as proof of her compassonate nature.
  • When Isshinta's tearful nature is played more seriously, this trope also comes forth. As he's about to pull a Last Stand for him, Hiko thinks he's glad to meet someone still able to cry.
• Tomboy and Girly Girl: The two Natsus, in a way. The Princess one is a shy and feminine Ojou, the Village one is an outspoken Tsundere.
• Water Works: Poor Isshinta spends half the time crying, either for comedic effects or for intense drama.
• You Are Not Alone: Isshinta's utter refusal to leave Hiko alone to his destiny ends up reigniting Hiko's desire to live no matter what, and fires him up enough to go to Nagumo and face Iwano and his troops.