Lunacy is the premium currency in Limbus Company, essential for acquiring new Identities and EGOs. As the game's primary gacha currency, amassing Lunacy is crucial for unlocking those coveted character variants.
Earning Lunacy in Limbus Company follows a pattern familiar to gacha game enthusiasts. Initially, you'll receive a substantial amount, but as you progress, the rate at which you acquire Lunacy will decrease significantly.

For newcomers, diving into the main story is the most effective way to earn Lunacy. Completing each chapter can reward you with approximately 390 Lunacy, and achieving an EX rating on missions can add another 260 Lunacy to your stash. To EX clear a mission, you must meet all the specific EX objectives, which, when done for the first time, grants an additional 40 Lunacy. Strive to meet these objectives to maximize your Lunacy earnings.
First-time clears of Luxcavation stages also provide Lunacy, though these rewards are one-time only.
Once you've exhausted the available story quests, your Lunacy gains will begin to taper off. At this point, consider the following methods to continue accumulating Lunacy:

Boosted Mirror Dungeons are likely to be your most reliable source of Lunacy. You can participate in up to three of these dungeons weekly, earning 750 Lunacy in total. These dungeons reset every Wednesday, so be prepared with your strongest Identities, as they can be challenging.
Events offer another excellent opportunity to earn Lunacy, albeit for a limited time. Participating in events whenever possible is advisable, and don't forget to review all event rewards to ensure you don't miss out on any additional benefits.
Uptying involves upgrading your Sinners' Identities and EGOs. As you progress through Uptie tiers, your characters become more powerful, and reaching Uptie Tier 3 rewards you with 40 Lunacy. While this method is not infinite like Mirror Dungeons, it serves as a long-term strategy for Lunacy accumulation. Continue leveling up your characters and gather Threads to eventually Uptie your entire roster.
Lastly, the game's battle passes offer a wealth of resources for enhancing your Sinners, including Lunacy. While the free tracks provide some rewards, unlocking all the benefits requires a real-money purchase.