The fourth collection of Stan Sakai's long-running Usagi Yojimbo series collects a long - some would say "epic" - storyline that started in 1989 and ran through six issues of the comic. It's largely the "gather all of the popular, previously separate, supporting characters" arc, and it has the same largely historical accurate but softened for tween readers tone as the rest of Usagi. [1]
In the interests of clarity, I should note that "Dragon" is a metaphor and "Conspiracy" is overblown: this is one feudal lord, conspiring with only his own lord and minions, planning in secret to launch a rebellion that could, potentially, maybe, topple the Shogun and would definitely knock off a couple of his local rivals and give him much more power and influence. "Dragon Bellow" is an artsy way of saying he's going to use guns to do that.
Thus Usagi Yojimbo Book 4: The Dragon Bellow Conspiracy. There are basically two intersecting stories, neither one of which initially involves Usagi, our rabbit-samurai hero.
In the main plot, good-guy (super-literally: he is drawn as a baby panda) Lord Noriyuki thinks his neighbor Lord Tamikuro is up to something mischievous. Tamikuro is a supporter of Lord Hikiji, the big bad of the series, who is continually scheming to depose the shogun. (Everyone seems to know this - perhaps except for the shogun.)
So Noriyuki sends a delegation to visit Tamikuro, led by the female samurai Tomoe Ame, who Usagi met and almost had a romance with in a previous story. And of course Tamikuro is scheming, having gathered a large stockpile of guns, and will be attacking Noriyuki any day now. Tomoe attempts to get back to her lord with the big news, but is captured.
Meanwhile, the ronin Gen (a big, mostly honorable rhino) is chasing the blind swords-pig Ino for the bounty on the latter's head. Both of them had been occasional allies of Usagi in the past, and they're heading through this same territory right now.
Usagi gets pulled into the story as he's also traveling through this region on foot: he sees Tamikuro's forces riding off with a captured Tomoe and tries to follow. But a rabbit on foot is no match for multiple...cats?...on horseback, so he's quickly left behind. He did hear her call out something about warning Noriyuki, and is torn between saving the damsel from unknown peril or warning the lord "hey, your samurai damsel is in some kind of peril." While pondering, he wanders into what had been a secret ninja village - they're like carpenter ants, there's one behind every hillside in this region - to find all the inhabitants had been slaughtered.
Quick background note, to explain what readers learned in bwa-ha-ha style gloating dialogue among the villains: this particular group of ninjas is opposed to Hijiki, for whatever reason, and has been spying on Tamikuro, trying to figure out his plans. So Tamikuro had his men slaughter their village.
Anyway, Usagi is an honorable rabbit, so he drags all of the dead bodies into one hut, in hopes some kin will eventually bury them. He is witnessed leaving the village, with not a little blood on him, by Shingen, a leader of those ninja, who has the reasonable misapprehension that Usagi was responsible. So he starts following Usagi to take his vengeance.
After more than a little swordfighting and yelling at each other, the good guys not in Tamikuro's prison - to sum up: Usagi, Shingen, Gen, and Ino - meet, work out their differences at least temporarily, and band together to assault Tamikuro Fortress with a force of those handy ninja.
There are battles, there are deaths, there is a conspiracy foiled. But, in the middle-grade friendly standard for the series, no recurring characters are harmed in the melee. As usual, I'm finding Usagi Yojimbo to be well-constructed, beautifully drawn, and compellingly told - but inherently a watered-down story for young readers. It definitely has a niche, but I'm finding that niche increasingly restrictive as the story goes on.
[1] See my posts on books one, two, and three for more details on the series, if you're interested.