How NOT to Summon a Demon Lord

How NOT to Summon a Demon Lord (original title: Isekai Maou to Shoukan Shoujo no Dorei Majutsu) is a classic isekai fantasy comedy with heavy ecchi and harem elements.

Quick synopsis: Takuma Sakamoto is a socially awkward, hikikomori gamer who dominates the MMORPG Cross Reverie as the ultra-powerful Demon Lord character Diablo. One day, he's suddenly transported into a fantasy world that mirrors his game — complete with his overpowered avatar, stats, gear, and abilities.

Two girls summon him hoping to enslave a powerful being to solve their problems:

• Rem Galeu, a petite Pantherian (cat-girl-like) summoner/adventurer, and
• Shera L. Greenwood, a busty, cheerful Elf.

They try an Enslavement Ritual to make him their servant... but thanks to Diablo's "Magic Reflection" ability, the spell backfires. Now they end up wearing magical slave collars and bound to him instead.

Unable to handle normal social interactions, Takuma decides to stay in full "Demon Lord Diablo" role-playing mode — acting arrogant, dramatic, and over-the-top to mask his anxiety. He ends up traveling with Rem and Shera, helping them with their personal issues (while they try to find a way to break the slave contract), fighting enemies, completing quests, and accidentally building a growing harem around his unstoppable power.

The series mixes action, overpowered protagonist fights, slapstick comedy from his social fails, fanservice, and light romance. There's a first season (12 episodes, 2018) and a second season titled Ω (10 episodes, 2021) that continues the adventures.

It's a fun, trope-heavy isekai if you enjoy OP demon lord protagonists, ecchi humor, and harem dynamics!