ShiriTra Joshi wa Pantsu wo Hakanai!: Dakara Haitte mo Muzai desho?

My childhood friend believed my lie and showed up for the training seminar without wearing panties, which totally aroused me... And when we stuck to each other, my dick slipped into her sleek entrance...!?
(Source: Coolmic)
Note: Simultaneously released in long-strip and traditional formats, with 18 episodes and 6 chapters respectively.