This episode was interesting for several minor things and also one major thing:
The police officers are starting to suspect the Ariake3 aren't really that completely out of contact with each other as Koichi would like them to believe. The statute of limitations is approaching and they clearly suspect the three siblings are planning something, but they don't what.
I liked how the three helped their old friend from the orphanage, but that seemed mostly like filler stuff. Also, the brief appearances by the earlier victims were a bit unnecessary.
The revelation of that guy they are planning to hustle right now as the son of the killer of their parents was already revealed in quite a few promotional comments about this drama. Still, they way Shizuna and Taisuke and Koichi found out about it was really well done. Especially the way Shizuna started crying when she tasted the hayashi rice because she recognized the taste.
This episode really confirmed that Koichi has a thing for Shizuna, even though she only views him as her brother, since she doesn't know of her parentage. His dream about them opening the restaurant and getting married really confirmed what had only been hinted at earlier in the drama.
Still, I keep being amused by Nakashima Mika's completely random and outrageous appearences in this show. And yes, it was very amusing how shocked Taisuke and Shizuna were that Koichi might actually have a girlfriend.
And on a very random note, it looked like Ryo was having great fun partying with George and acting outrageously in silly clothes in this drama. Probably quite a difference from the quite serious and moody roles he has had before this :D...