Further notes

Dr. Birkin's transformation saw him go through a number of mutant forms. There were five distinct stages of his evolution, though these included intermediate stages as well. They are dubbed "G1" through "G5".


Birkin 1

Dr. Birkin's initial mutation kept much of his body unchanged, with the mutations only being seen on the right side of the body, with the arm, torso and face being affected as it was on this side of the body he was shot. The left side of the body is more recognisably human. The heavily mutated right arm was noted as exhibiting superhuman muscular strength, allowing him to tear off iron beams from railings. A side-effect of maintaining a human brain was occasional bouts of dizziness.[1][excerpt 1] The G1 form appeared in two stages, distinguished by the appearance of claws on the mutated right hand, which were used on 23 September to kill a number of USS operators. By the night of 29 September Dr. Birkin had evolved to no longer require them, instead having an enlarged but otherwise human hand capable of handling weapons.


Birkin 2

The G2 form experienced the growth of a new head and brain to replace the original, the face of which descended to the torso's left side. The torso in general sees an increase in size, becoming wider as not only the skeleton and muscles are changed but two new arms begin growing asymmetrically under both shoulders. The legs also become thicker, with the tibula and fibia increasing in length. The mutant right arm also went through further changes, regrowing the claws it once had early in the G1 stage.[2][excerpt 2]


Birkin 3

The G3 form saw the increased symetricalisation of the body. The legs became black and dark grey coloured, with the growth of an eye on the left thigh. The two new arms grow further and became the same size, and grew their own shoulders to descend from. The original two arms were pushed backwards and kept their own shoulders, which allowed for the proper use of four arms. The vestigial human face shrunk in size and positioned itself against the front left shoulder. The G3 form also continued the changing movement of the heart; positioned near the shoulder in the G2 form, it moved to the middle of the upper torso. This form has been noted for its demonic appearance.[3][excerpt 3]


William Birkin 07

Following damage sustained in his G3 form, Dr. Birkin mutated to the G4 form. This form saw a radical change in gait, going from bipedal to quadrupedal as the two largest arms became legs. G4 saw an enhanced mobility surpassing the G3 form in spite of losing its high-jumping skills. A large mouth has formed out from his chest out of ribs that previously protected the heart. The need for such a large mouth was so the creature could satisfy its increasing demands for energy.[4][excerpt 4]


1070732-g type mutation 5
The G5 form was a further degradation of the G4 form. The mouth and digestive system of G4 remained to support the massive nutrient requirements. Whole bodies were consumed by G5, which could eat even Zombies. However, these were digested over time, and partially consumed and recognisably-human biomass covered its surface. The body itself became more mollusk-like in appearance, though propelling by using four tentacles to drag itself along.[5][excerpt 5]


  1. Excerpt from Official Guide Book, p.53: "大きく右肩がせり出した左右非対称の姿は、 人間の原型をとどめているだけに、 その異様さが、 よりきわだって映る。 変形の初期段階である現時点でもゾンビとは比較にならない耐久力を有し、 G細胞に浸食された右腕は鉄柵を容易に引きちぎるほどの怪力を誇る。 ときおりめまいに似た不安な動きを見せるが、 これはG生物化によって身体の質量が大幅に増加していることに起因する。"
  2. Excerpt from Official Guide Book, p.54: "左腕をのぞいた上半身全域にG細胞の浸食が進み、 ベースとなった人間の頭とは別に脊椎付近から新しい頭部が造り出されている。 それにともない内部の骨格は大きく変貌しており、巨大な右腕のツメも、 手の先の骨が尖鋭化し、出し入れ可能になったものと推測される。 なお、 その姿から判断して、 Gの脳はまったく新しいものが形成されている模様。"
  3. Excerpt from Official Guide Book, p.55: "増殖したG細胞が下半身にまで到達し、 眼球状組織が新しく左大腿部にも発生した。 第2形態で生じつつあった補助腕が、 通常の腕と遜色ないまでに発達をとげ、 背中に大きく張り出した本来の腕は、 有翼の悪魔を連想させるシルエットを作り出している。 降起した胸部には巨大な心臓があると考えられ、 循環器系にも異変が起きていることがうかがえる。"
  4. Excerpt from Official Guide Book, p.56: "G細胞の増殖もともない進行なるGの形態変化は、生命危機に即応した超回復によっても引き起こされる。この段階では、 2足歩行をやめ獣型になることで、 人型では実現しえない高い運動性を獲得した。 頭部と一体をなす胸部の大アゴは、 食物摂取をより活発に行なうためのものと考えられ、 体格に比例してエネルギー需要が高まっていることを裏づけといる。"
  5. Excerpt from Official Guide Book, p.58: "第4形態で食物を大量摂取したことを反映して、 身体の質量・体積がかつてないほどに増大している。 4本あった腕は触手に変形し、 せまい場所にも器用に侵入する軟体動物のような身体を得るに至った。 体表を覆う未消化物質には人型の肉塊も見てとれ、 研究所のゾンビたちをエネルギー源として取りこんでいたことがわかる。"
  1. Tahara (ed.), Official Guide Book, p.53.
  2. Tahara (ed.), Official Guide Book, p.54.
  3. Tahara (ed.), Official Guide Book, p.55.
  4. Tahara (ed.), Official Guide Book, p.56.
  5. Tahara (ed.), Official Guide Book, p.58.
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