Samurai Sentai Shinkenger/WMG

NOTE: This Wild Mass Guessing contains Epileptic Trees that may spoil the intense storyline of Shinkenger. Visit this particular grove at your own risk!

The Shinkengers are all related to a greater or lesser extent
None of the current batch are closely related; but, given that their families have been working together in close proximity for 18 generations, it would defy human nature if there weren't any romantic entanglements among or within the various teams. Genta being the first ShinkenGold is the exception.

Genta, DaiGoYoh, the Ebi Origami and Ushi Origami will be critical in defeating Doukoku once and for all
None of the previous generations had a Sixth Ranger. Genta was the one who created the Ebi Origami and DaiGoYoh, and so they've never been involved in the climactic battles before. The Ushi Origami (and its combinations) are older, but they've been sealed the entire time, so this applies to them, too.

The Nanashi can evolve into Ayakashi like the Rinshi turning into Rinrinshi from Gekiranger
The Gedoshu are the basis of the various obake and youkai that crop up in Japanese legends. But if they've been pruned back by 18 generations of Shinkengers, then either the current batch have been powerful enough to survive to create legends or they have some way of replenishing their numbers.

Assuming the second option: a defeated Ayakashi's spirit returns to the Sanzu River and possesses a Nanashi and eventually restores themself, but this takes a long time. So the gap between attacks are caused by the Gedoushuu waiting for enough Nanashi to turn into Ayakashi.

The cost of the Battle
While there is no show Canon or Word of God to this effect, fan speculation that all the current Samurai-tachi's parents served under the prior Shinken Red leads to some interesting thoughts. Besides Takeru's father dying, the flashback in episode 12 suggests:


 * Kotoha's mother took a sword blow across the stomach. This adds a whole new layer to her older sister's concern when Kotoha took on the mantle of Shinken Yellow-- if they grew up knowing that mom took that kind of blow, then it would make the danger of being a samurai very real to them.
 * Mako's mother being a paraplegic is consistent with the sword blow across the upper back she took. Act 38 makes the effect this has on Mako's life clear, though it is hinted at in act 13.
 * Chaiki's father, who we see taking a Renku's own sword to it and its other nameless fellows, was knocked prone and stabbed in the side or abdomen. His expressed desire for Chaiki to be a happy child, who choose to be a samurai rather than being forced, may be a touch of Post Traumatic Stress-- or simply the wisdom of a man who got off light in such a deadly situation, compared to his Lord dying and Mako's mother. (Seriously, you normally can't get much worse than a stomach wound!) And:
 * Ryunosuke's father, who apparently took Three. Flaming. Arrows. To his chest. This puts his father's command in Act 1 to do well in their performance that day in a whole new light -- his comment "It may be the last" could be born of the experience of being injured in the raid. It also gives plenty of motivation to be as stern a samurai master as a kabuki master to Ryu-san.
 * The effect of the raid on Kaoru, our hidden true clan head, is less certain, given how little we know so far-- but it may have motivated the Shiba to put her in hiding in the first place. What is known is that her mother was possibly pregnant with her during or after the raid. Also, her reference to her father while attempting the seal suggests that, at the least, she hopes her father's sacrifice was not in vain.

Shitari will return with a revived Dokoku.

 * How else are they going to pull off a team-up with the Goseiger?
 * Jossed. Shitari returned, but Buredoran, Goseiger's Big Bad, had Dokoku's powers.

The Shiba clan in this show is the same one in Bleach

 * But the clan symbol is too different!
 * They obviously changed it when they moved to the living world

The Jidai Geki illusion in the beginning Samurai Sentai Shinkenger Returns reflects how each of the families started out before becoming the Shinkengers

 * The Shiba were originally ronin who gained status after being able to defeat the Gedoushu. The Ikenami were other ronin or mercenaries who fought alonside the Shiba. The Shiraishi were geishas or courtesans. The Tani were thieves or vigilantes of some kind. The Hanaori were ninjas. And, yes, the Umemori only just became samurai with Genta, but his anscestor was likely making tasty helpings, if not serving up sushi.

The sci-fi illusion in Shinkenger Returns is based on the dreams of the Origami.
While the first six illusions seem to all be connected to the Shinkengers, the sci-fi scenario doesn't really fit any of them in particular. Therefore it must belong to the Origami, which were with the Shinkengers when they were captured. The Origami view themselves as the spaceship, which is itself struggling to survive along with the team.