The last episode has the most nudey service of any episode in the show.
(From the ED):
Overall Ayakashi Triangle the anime is okay, but does not live up to the manga original. The low budget of this series makes the art a pale imitation of Yubuki’s talent, which is too bad. Even worse, the series at times omits entire nude scenes and covered surprisingly little ground (ending at chapter 24, covering only three tankobon volumes in twelve full length episodes). For comparison’s stake, an anime of this length will usually cover four or five volumes, and back in 2015 the Triage X anime even covered nine volumes in just ten episodes.
If the plan is to come back with future seasons and/or OVAs to cover the rest, like was done for To Love-Ru, then all is well. But that seems pretty unlikely given the production value here, and the current climate in which almost no ecchi gets produced anymore.
On the plus side, the series did avoid the temptation of an anime original ending, it stayed true to the manga all the way through. This suggests that the production is at least open to the possibility of future episodes, as unlikely as that might be. And towards the end, the nudity actually started to expand on the scenes from the manga slightly. In the final episode, many nude parts do not have manga panel equivalents. If there were another season announced, that would be a little exciting, because the next section of the story is where the service starts to pick up significantly.
As is obvious from the screencaps, nudity will have to wait until blu-ray. The first blu-ray actually came out today (9/27). Volume Two will release on 10/25 and Volume Three on 11/23. This follows a fairly standard practice of releasing six BDs, one per month for six months. Should hopefully have the first nude screencaps to share soon.
Overall, this was a mid-level nude ecchi anime in year that had just two nude ecchi series all year long (including what looks like a barren Fall season). The other being Inuhiro from the Winter season to start the year. Next year might be a little better, with Chained Soldier and 2.5 Dimensional Seduction both getting solid productions by reputable studios, and are based on super lewd nude ecchi manga.