Boukyaku no Senritsu

A list of anime containing ecchi elements, but are not tagged as ecchi by MAL. While the ecchi content may not be as prevalent or extreme as officially-tagged ecchi titles, there is still enough to be of interest to fans of the ecchi genre. Many of these register at least 1.5/3 stars on AniDB's "tag-weighting" system for ecchi.
Conversely, those who don't care for ecchi may wish to use this stack for cautionary purposes, as these titles may contain things like pantyshots, revealing outfits, incestuous overtones, oversized/jiggling breasts, swimsuit/lingerie moments, extended bath/shower scenes, lewd dream/fantasy sequences, innuendo, or general fanservice in an otherwise serious/"respectable" show.
Only the first seasons of franchises are listed. Some titles may (eventually) have additional details explaining why I've placed them on the list.

Part 1: https://myanimelist.net/stacks/24838
Part 2: https://myanimelist.net/stacks/26746

I can’t say these titles are good, but they are unforgettable.
This is a list to compile the odds and ends I recommend for no reason other than they exist.

For anime which have 20+ episodes and only one opening and one ending

On May 29,2024 anime studio Gainax filed for bankruptcy, and thus became the final nail in the coffin of the once great titan of the anime industry. To many this came as no surprise. Decades of bad business decisions had finally caught up to them. But still it was sad to see them go. However, rather than dwell on the depressing aspects of Gainax fall from grace, I would rather look back on the legacy they built.
The studio was formed in the early 1980s as Daicon Film by university students Hideaki Anno, Yoshiyuki Sadamoto, Hiroyuki Yamaga, Takami Akai, Toshio Okada, Yasuhiro Takeda and Shinji Higuchi. After the success of their first two anime shorts for the conventions of Daicon III and IV, they firmly established themselves as a talented new anime studio. They would later change their name to Gainax in 1985, basing the term "Gainax" on an obscure Tottori Prefecture term for "giant", with the English suffix -x added because it sounded "good and was international"
Gainax presented themselves as a “by fans, for fans” studio and through it’s ups and downs Gainax lived up to that phrase, for better and for worst. Though the studio is now gone, it’s legacy will live on through both studio Trigger and studio Khara. Here is the list of from the house that Gainax built.

Notes: With a few exception, sequel seasons and/or movies will not be included on the list so that there is room for everthing.
Notes: Even though only the last Rebuild of EVA film is on this list you should watch all of them.
Honorable mentions: There are two anime at the end of the list that warrant being a part of the Gainax legacy. Punch Line was directed by Yutaka Uemura, who also directed Dantalian no Shoka, has a style and story that would be right at home with other Gainax shows. Finally, Grendizer U, produced at studio Gaina, formerly Fukushima Gainax, honors old Gainax’s fandom roots.