Subplots to the series concern Kouga's slow-boiling romantic relationship with Kaoru who is trying to get her first picture book published while Kouga tries to keep his seal a secret from her, Rei/Zero having also been marked with the seal and a possible resurgence in his friendly rivalry with Kouga, and the identity of the series antagonist, a red-masked Makai Priest who "seals" Kouga and Rei as part of his effort to destroy all of the Makai Knights and make the Priests dominant again.
Also introduced is the Makai Senate, which heads the Makai order and therefore over-rules the Watchdogs shown in the previous series. The senate includes Grace, a high ranking Makai Priestess and gives out orders in place of the Watchdogs and Kouga's new partner Reo Fudō, a kind hearted Makai Priest and creator of the Gouryu previously seen in the film Red Requiem. Reo is also seen to be troubled by memories of a woman (known as Mio) from his past, whom Kaoru reminds him of.
Another amazing series, this one focuses more on the romance aspect of kouga and kaoru. This second series doesn't let down its prequel. it's still badass as ever, with amazing action and some romance now. It makes you feel one with the cast, makes you fond of them. Do note that there are movies in between so if you want to watch these, then wiki it up to watch it accordingly so you do not miss out on anything. Enjoy!!!