High school student Hoshi Izumi (Nagasawa Masami) loses her father suddenly in an accident. One day, Sakuma (Tsutsumi Shinichi), the waka gashira of a small and weak Yakuza gang in Asakusa – the Medaka Gumi – pays Izumi a visit along with the gang members. The death of their former kumicho (Boss) puts Medaka Gumi on the verge of a breakup. Therefore, Sakuma begs Izumi, the former boss’s only distant relative left, to succeed to the kumicho position. Izumi is taken by surprise and keeps refusing at first. However, she ends up becoming the 8th kumicho of the Medaka Gumi!

The police tell her that her father’s death may possibly be a homicide case. There’s also Mayumi (Koizumi Kyoko), a mysterious woman staring closely at Izumi’s father’s photograph at his funeral. The situation becomes complicated when the drug-dealing vicious yakuza, Hamaguchi Gumi, comes into the picture as well as Sandaiji Hajime (Ogata Ken), a politician whose public stance is to eliminate drugs.


Cast
* Nagasawa Masami as Hoshi Izumi
* Tsutsumi Shinichi as Sakuma Makoto
* Nakao Akiyoshi as Sakai Kenji
* Taguchi Hiromasa as Nishino Takeshi
* Yamamoto Ryuji as Sakai Kinzo
* Fukui Hiroaki as Goda Hideki
* Katsura Kokinji (桂小金治) as Medaka Tatsuo
* Koizumi Kyoko as Mayumi
* Ogata Ken as Sandaiji Hajime
* Hashizume Jun as Hoshi Takashi
* Koichi Mantaro as Kuroki Kohei
* Izawa Ken as Inaba Michio
* Honda Hirotaro as Hamaguchi Noboru
* Mori Ren as Mori Ranmaru
* Okayama Hajime as Iwakura Tomoo
* Nakao Hideo (中野英雄) as Shibata Mitsuaki

Guests
* Nukumizu Youichi as Veterinarian (ep1&6)
* Sugiura Sosuke (杉浦双亮) as 1st floor resident (ep1-5)
* Morimoto Yuko (森本ゆうこ) as Kaneda Reika (ep1-5)
* Ihata Juri as Tokiwa Kazuko (ep1-5)
* Tani Arisa (谷亜里咲) as Kobayashi Akemi (ep1-5)
* Aoki Kazuyo (青木和代) as Izumi's aunt (ep1)
* Mizumori Kota (水森コウ太) as Izumi's uncle (ep1)
* Miho Jun as Lily (ep2)
* Takeno Isao as Aoki (ep2)
* Moriyama Yonetsugu (森山米次) as Zenzo (ep2)
* Konno Mahiru as Tetsuka Naoko (ep3)
* Tanaka Koutaro as Tetsuka Yuji (ep3)
* Yashiba Toshihiro as Reporter (ep3)
* Imai Yuki