Whether you are going to watch this anime because of plot or the other plot, it's worth either way. Set in a parallel version of the Taihei Edo period, the series follows the busty samurai, Chifusa and her attendant Kaede.
In Manyuu Hikenchou, it's all about breasts. Breasts give you power, fame, wealth and respect. And so as you've realized, the plot revolves around breasts, the bigger the better. Chifusa and her attendant Kaede travel around the Japan to reach its final destination, Chifusa's home village in order to learn the ultimate technique: Breast Flow (乳流れ Chichi-nagare). Chichi-nagare allows to control the form of breasts and thus allowsr to enlarge or reduce breasts. But only Chifusa's clan is able to master this technique and Chifusa's goal is to give all women bigger breasts in order for them to be happier because if you're a flat chested girl in Manyuu Hikenchou's world, you're worthless.
Art and Sound (8/10)
Absolutely delightful art style, female character are obviously more detailed which I'm sure no one will complain. I did slightly find annoying that each episode(1-5 episode only) Chifusa's breasts from far out in her clothes almost looked the same but once nude. they looked huge.
Sound was top notch, the soundtrack was catchy and the vocals by AiRI were always a pleasure to hear (She's also in Tari Tari and Gundam Build Fighters). The voice actresses are no surprise and done their job flawlessly with great acting, but what I enjoyed most was definitely the traditional japanese music during Edo period, absoutely lovely and a joy to my ears.
It wasn't "perfect" but it was definitely well developed, specially Chifusa and her sister Kagefusa. Chifusa's realization of her selfishness and the change she made was unexpected thing and it's not really often seen in ecchi animes. Same goes for Kagefusa who held a grudge but in the end was in tears and smiled after hugging her sister. Also the amount of characters we meet in these 12 episodes is large. Definitely not a bad thing for me, always enjoy seeing other characters and their personalities. Only problem is, they're given way too few time on the screen.
As I've written in the beginning, whatever the reason is you want to watch this, it is absolutely worth it. You have everything you want, swordplay, comedic scenes, beautiful music, adventure, plenty of character and most importantly: A lot of breasts.
Ecchi animes are often low rated, and most of the times, it's deserved. But, Manyuu Hikenchou despite its ridiculous plot as some say it the main subject of anime(breasts) actually are connected to ours world. It's funny but in today's world, for the most of the people, if you have big breasts you're worth more than a flat chested girl and that is exactly what Manyuu Hikenchou shows, the life of two sides, one is a enjoyable one, the other one is a horror. Believe it or not, despite the fact that 70% times they show breasts the anime does send a good message.