You're not sounding quite like yourself there, Iku.

Iku's parents' visit is imminent - and though she's asked the library staff to aid her in deceiving them, she's still incredibly nervous. The plan is to have Iku masquerade as a library administrator for a day. As highlighted in previous episodes, Iku's librarian skills are less than spectacular. It doesn't help that the latest magazine article featuring the Kanto Library has an image of Iku escorting Commander Inamine to the ambulance.
This episode mostly involves the antics of Iku and the library crew trying to prevent her parents from finding out she's in the Task Force. That being said, I'll try to keep it short and sweet.
Upon arrival, Iku's parents want to have a tour of the library, which Iku tries to get out of. Eventually, she gets Ayase to help her, with the promise of buying Ayase lunch later. At the cafeteria, they run into Genda, who is about to account for Iku's heroism from the previous episode when Doujou jumps in to drag him off. Despite this, Genda still manages to get in an offer to have Iku's parents stay overnight.

Genda is really, really tall. o.o

In Iku's room, her mother finds her defense force uniform, but Ayase saves the day by saying it's hers. Iku's nervous because it's obvious that the uniform is too big for Ayase. The latter saves the day by saying it's her boyfriend's. Bathing later, Iku's mother comments on how polite and ladylike Ayase is.

The next day brings more troubles - Iku's mother wants to read the latest article regarding the Kanto Library. Well, we all know what's in that. In order to prevent her mom from reading the article, she goes so far as to ask Doujou to hide it for a day. Uh oh censorship~ Doujou reminds Iku of the library's code. (As well as the very point of conflict in Toshokan Sensou) Iku manages to stall her mother one magazine after another. However, her father tests her librarian capabilities and finds them severely lacking.

Suddenly, a commotion erupts and a thief tries to make off with a book. Iku immediately jumps into action, chasing the thief down and apprehending him. This event is unavoidably witnessed by Iku's parents. Later, Iku's mother really wants her to quit the library. Iku becomes angry and is about to run off when her father tells her to stay. He then convinces Iku's mom to let Iku continue at the library. When her parents leave, Iku mentally apologizes for not telling them the truth.

Back in his room, Doujou finds the magazine on his desk, with the article of Iku dog-eared. It appears that Iku's dad really did know.

Thoughts:
I know this is late! I've been waiting for Frothbite-Menclave to release their subs. A number of people who watch Toshokan expressed their discontent with Ocha! subs, so I thought I'd go ahead and avoid them.
The episode itself was touching, especially at the end. Of course, Iku's mother doesn't really earn any points, since it was her father that knew everything and decided to let Iku follow her dreams.
I am SO behind on this, though.