So I'm trying to unlock some more achievements and I'm trying to figure out where exactly I can get them. If anyone could direct me to the right place/mission/whatever that would be great.

I'm looking for an opponent named Noah, Pashmina and Akira. And Mission tutoring teacher? O_o There's several achievements based around this. Basically I'm trying to collect pieces of the Sakyubasumeiru armor set (it's dark brown armor with horns, used by the lvl 200 Xiphos on Sairenji Island sometimes). Any help starting out for these parts would be highly appreciated.

I think there's 7 pieces to this set (Succubus Mail set), and the pieces are unlocked by completing the following missions:

Arm: "スプリット・ヴァイス" (Team Mission)
Thigh: "白き幻影" - Unlock this mission by completing 6 Secret Missions. The missions listed below are all secret missions.
Lower leg: "ビッグウェーブ" - Unlock this mission by beating Extra Mission XVI 10 times.
Waist: "ラジオロンドからの刺客" - Unlock this mission by beating Journal Mission III 100 times.
Body: "復讐のジュデッカ" - Unlock this mission by beating Illegal Mission VIII 10 times.
Shoulder: "先生の課外授業" - Unlock this mission by beating C-Class I Mission 100 times.
Horn: "ノアの逆襲" - Unlock this mission by beating Journal Mission V 100 times.

Other than the 6 listed above the other 2 Secret missions are "忍びの仇討" (beat Journal Mission 6 100 times) and "全能なる者" (win a battle using the skill "完全なる停止“kill -9”').

awesome thanks a lot ^^