Aniplex's second installment in its scheduled three-part release of Durarara!! covers episodes 10-17, which wraps up the arc focusing on Celty's active quest for her head and contains the entirety of the main Slasher arc. It also includes episode 12.5 (the one involving the supposed aliens), a stand-alone intermission which was originally a DVD-only episode. Along the way the series shifts from its character introduction phase into its character and plot development mode, with some juicy results. Although these episodes are not without their weak points, the series' quirky spirit strongly persists as it delivers a highly entertaining run of episodes which includes the startling truths behind the natures of the Dollars and the Slasher, what really happened to Anri's friend Mika, and the situation with Celty's head.

And it is that plethora of sharp twists, turns, and revelations which give these episodes some of their greatest appeal. Most prominent characters introduced so far get caught in up these dramatic shifts; even the sexual harassment-prone teacher who has been interacting with Anri has his own twist, and one atypical for a character like him, too. The first big culmination of these developments comes in episode 11, when the trouble stirred up by a certain head wandering around Ikebukuro directly leads to the first in-person meeting of the Dollars, a wonderfully-executed scene well worthy of having been chosen by reviewer Carl Kimlinger as his Scene of the Year for 2010; even if you have guessed who many of the Dollars are, you will not have guessed them all. That is just the first of many surprising major developments, however, and that includes the way the series is plotted. The whole business with the Slasher, especially what the Slasher's motives are, plays out in a novel way and with connections that run much deeper into the series' backstory than will initially be apparent. In fact, the presence of Izaya in the story assures that everything is more connected than is initially apparent.

The other main draw is the fun factor of watching all of these oddball characters interact with each other and deal with oddball situations. Celty gets the greatest attention and considerable more opportunity for character development, which saps her mysterious and flagrantly cool side in exchange for creating a supernatural creature whose idiosyncrasies run deeper than most humans; the notion that an immortal, headless woman could be afraid of aliens, freaked out by a hard-nosed cop, or girlishly in love is inherently amusing. The whole “I love you even without your head” relationship that she has with the doctor isn't even the most perverse romantic relationship in the series, either, and then the doctor's even loonier father shows up. Mikado's hesitant actions towards Anri are more typical and bland, but Anri and Masaomi both get developments only vaguely hinted at in the first part. Shizuo has several moments of his own, including a glorious action scene where he gets to show off the true extent of his strength, and Izaya continues to redefine what it means to be an ass.

The structure of the series also continues to draw inspiration from some of anime's least conventional series, with clear influences from both Boogiepop Phantom and Baccano! still pervasive. Perspectives shift with each episode (and often within each episode), events sometimes repeat from alternate perspectives, and the bonus episode mostly plays out backwards. Like both of the aforementioned, this is also decidedly an ensemble cast show, as even Celty and Mikado only marginally get more attention and focus that other major characters and even they take back seats in some entire episodes. Unlike its predecessors, Durarara!! continues to glory in all of the anime and manga references it casually or deliberately tosses off, the most prominent being a couple of appearances by two characters from Baccano! – and given who they are (fans of Baccano! shouldn't have to guess), it is entirely plausible for those two characters to show up here, rather than just being the normal out-of-context cameo appearances, if one assumes that the two series share a common universe.

The artistry merely continues the standards set by the first third, with the only special new elements being a cool coloring trick pulled off in the scene where the Dollars gather and Shizuo's big fight scene. The practice of only coloring featured characters in crowd scenes is still an interesting gimmick but is also starting to feel a little lazy, especially combined with the rough edges of some characters and the simplified animation in some action scenes. The series can look sharp at times, does integrate in a lot of setting detail, and has some impressive use of CG effects, but there are definitely prettier series out there.

The musical score also continues with the themes it established in the first third, although this is more of a plus. Makoto Yoshimori effectively uses his laid-back and light-hearted themes to promote the playful mood of scenes and comes up with some nice options for the more dramatic moments. Episode 13 institutes a new opener and a new closer, neither of which (especially in the case of the opener) is quite as good as the originals.

In these episodes Bang Zoom! gets its best English dub performance from Kari Wahlgren, who truly shines in capturing all of the personality quirks that spill out from Celty's headless body, but that is hardly the only good performance or wise casting decision. In fact, the dub's only real failure is recasting the characters from Baccano!, as the English voice actors used here neither feel nor sound right compared to the original English performers. The English script varies between being dead-on and broadly interpretive, but aside from the aforementioned flaw this is a top-rate dub job.

Aniplex splits the nine episodes across two disks which come in a case that, like the first part, has a see-through slipcover marked with police tape. Included in the case are series-themed postcards, while the second disk has a pair of music videos featuring the full-length, live-action versions of the original opener and closer. Aniplex also apparently has this warped notion that the English credits should classify as an Extra. (The openers and closers have the original untranslated credits.)

Many have claimed that Durarara!! decidedly drops off in its second half, but episodes 13-17 show little evidence of that. The pitfalls the storytelling has during this time – excessive use of introspection, nothing interesting about its teenage romantic relationships, relies too much on narration – have been pitfalls since the early episodes of the series, and events in the second arc are no less dynamic. If the writing is off after episode 12, it is only by a small step. There is still plenty enough going on at this point to keep a fan's interest and the end of episode 17 gives the promise of much more to come.