Marie accidentally discovers that Kang-se and Poong-ju are brothers, while Poong-ju finds out that she and Kang-se are romantically involved. Meanwhile, Do-ki's subtle interest in Marie becomes harder to ignore, bothering Kang-se. As Eun-kyung suggests setting up Si-ra with Poong-ju, Suk-hee grows uneasy. Kang-se prepares a little surprise to celebrate his 100-day anniversary with Marie.
