L-BaCus, also known as LINE+ Back Customer, is a customer-acquisition and LINE marketing tool offered by Accel Marketing Co., Ltd., a Japanese digital advertising and web marketing company. It helps businesses reconnect with prospective customers who leave their websites by inviting them to communicate through LINE, then nurturing their interest and encouraging them to return and convert. The service supports industries including e-commerce, financial services, recruitment, matching platforms, cosmetics, beauty clinics, and used-car sales.

L-BaCus offers customizable messaging scenarios based on traffic sources, push notifications, exit-intent pop-ups, and tools for guiding users through LINE. Its team provides implementation and ongoing operational support, including scenario and banner creation, tag setup, reporting, A/B testing, creative adjustments, and campaign recommendations. The company states that setup and monthly fees are zero, with performance-based compensation; actual results and costs depend on each business and its advertising circumstances. Businesses can review performance in a dedicated management dashboard and define conversion goals to suit their products or services.