Kazuya Nakai
Kazuya Nakai is one of those guys that you've more or less seen around before in many different games or anime that you've watched. His voice is distinctive and very easy to identity, he's got a really rough pitch that usually works for those tough guys or scruffy bishounens. Still, when he nails a role down he does it damned well that's fitting of the character that he voices, so that's all good. His most famous roles include Date Masamune (Sengoku Basara Series), Zoro (One Piece Series) and the more recent Zapp (Blood Blockade Battlefront), who is, in my opinion, the best character that he has voiced thus far. He can be the big brother figure with characters like Marito (Aldnoah Zero), Waka (Final Fantasy 10) or Zaka (Valkyria Chronicles). He can be that one crazy dude like Gilgamesh (Final Fantasy Series), or the delinquent student in Suguro (Ao No Exorcist) and Mundo (Danganronpa). Finally, he can run the occasional pretty boy in a charcter like Soma (God Eater), who doesn't actually say much in the first place.
Characters from left to right
1st row - Marito (Aldnoah Zero), Waka (Final Fantasy 10), Gilgamesh (Final Fantasy Series), Zoro (One Piece Series)
2nd row - Date Masamune (Sengoku Basara Series), Soma (God Eater), Zaka (Valkyria Chronicles)
3rd row - Suguro (Ao No Exorcist), Zapp (Blood Blockade Battlefront), Mundo (Danganronpa)
Rumi Ookubo
Rumi Ookubo is a rather new seiyuu in my opinion. She started doing major roles in the early years after 2010, and she's had her fair share of lead roles in them. She can be quite versatile if she needs to be, but most of the time she's stuck doing cute characters with various, different tones. In a way, she's more of a moe voicer than anything, something along the lines of Ayane Sakura. Still, she has some characters I really like. She's able to go tsundere like Alyn (Fairy Fencer F) and Yuzuki (Black Bullet), though she's more on the cute side for these characters. More "normal" high school girl characters include Hiragi (Freezing) and Kazuki (Gallilei Donna). Then we have the uber cute-sy girl with a troubled family background in Usagi (Anti-Magic Academy:35th Test Platoon) and the battle hungry little girl in Botenmaru (Oda Nobuna No Yabou). Finally, my favorite archetype from her, the hybrid girl with a crazed side, either the fujoshi Tamako (Barakamon) or the Momoka loving Urara (Sabagebu).
Characters from left to right
1st row - Hiragi (Freezing), Urara (Sabagebu), Kazuki (Gallilei Donna)
2nd row - Tamako (Barakamon), Yuzuki (Black Bullet), Botenmaru (Oda Nobuna No Yabou)
3rd row - Alyn (Fairy Fencer F), Usagi (Anti-Magic Academy:35th Test Platoon)
Ryoko Shiraishi
Mm-hmm, that's a nice cast of hot and sexy ladies. Ryoko Shiraishi's voice is a little bit on the deeper end for most female seiyuus, because of that, she's really not the type to voice the uber cute/moe characters like Yukari Tamura or Aki Toyosaki would. Instead, she's more fitting for the more...well endowed ladies. We're talking about those bombshell characters like Makkiko (Kyokai Senjou No Horizon), the female version of Kokurri-san (Gugure Kokurri-san) and the fabulous Suginami (Anti-Magic Academy:35th Test Platoon). She also does amazingly well with the Kansai accent with characters like Hikage (Senran Kagura), Asuka (Tekken Series), Kagenui (Monogatari Series) and Himeko (Sket Dance!). How about them half-breed bishonen/bishoujo guys?! She's got Sakuragaoka (D.Frag) and Hayate (Hayate No Gotoku series) in her resume as well! Finally, she's voiced Macaron (Amagi Brilliant Park), which is the most hilarious piece of shit stuffed animal I've ever seen, only second behind Tyramie from the same show.
Characters from left to right
1st row - Macaron (Amagi Brilliant Park), Asuka (Tekken Series), Kagenui (Monogatari Series)
2nd row - Hikage (Senren Kagura), Makkiko (Kyokai Senjou No Horizon), Female Kokkuri-San (Gugure Kokurri-San), Sakuragaoka (D.Frag)
3rd row - Hayate (Hayate No Gotoku), Himeko (Sket Dance!), Suginami (Anti-Magic Academy:35th Test Platoon)
Hiroki Yasumoto
Alright, move over, its time for the big boys to play. Hiroki Yasumoto's voice is mighty strong, in fact, its so powerful that its practically a must to cast this guy on those big, buff, badass guys, or he'll make your day a living hell. His voice is deep and powerful, making him a well fit for intimidating characters. Whether or not he HAS to voice villains all the time is up for debate though, because he voices a multitude of nice guys that are usually bros to the MCs in their respective shows. I'm talking about Agil (Sword Art Online Series), Tobita (Gate), Bomber (Himouto:Umaru-Chan) and Chad (Bleach Series). Then there are the nice guys that just look hella scary, like the Vice President (Daily Lives Of High School Boys) and King (One Punch Man). He also voices honor bound individuals like Guile (Street Fighter IV) and Vlad (Aldnoah Zero). My 2 favorites are his incredibly out of character Kobold (Kyokai Senjou No Horizon) and the insanely canonically overpowered Azrael (Blazblue Series).
Characters from left to right
1st row - Vice President (Daily Lives Of High School Boys), Guile (Street Fighter IV), King (One Punch Man), Kobold (Kyokai no Senjou No Horizon)
2nd row - Agil (Sword Art Online), Tobita (Gate), Bomber (Himouto:Umaru-Chan), Vlad (Aldnoah Zero)
3rd row - Chad (Bleach Series), Azrael (Blazblue Series)
Yuu Asakawa
I'll just have to say "Yes, One-Chan", and I'll be a happy man. Yuu Asakawa's voice is meant for all the strong, sexy, girls out there that are looking for a fight, and I love it. The characters she voice all feel like they'd either make good big sisters or just straight out female gang bosses, which is great going with her intimidating, yet sexy, voice. First of all, she voices the insanely fabulous and popular vocaloid, Megurine Luka (Vocaloid), Secondly, she is the mainstay voice for Rider (Fate Series), that alone says something. Anastasia (Brave10) also shares that same aura of badassery, while girls like Arnett (Freezing) and Momoya (Majikoi) are more in the group of "High School Girls That Are Really Powerful And Act Like One-Sans". Finally, she's got the 2 sided Jess Beckham (Nobunagun), the silent, cool nurse beauty of Chitose (Shinmai Maou No Testament) and the fun loving Leone (Akame Ga Kill).
Characters from left to right
1st row - Anastasia (Brave10), Leone (Akame Ga Kill), Arnett (Freezing)
2nd row - Momoya (Majikoi), Chitose (Shimai Maou No Testament), Jess Beckham (Nobunagun)
3rd row - Megurine Luka (Vocaloid), Rider (Fate Series)