Study through Eroge

Hello,

I am trying to read through an Eroge. With most online resources, I can find meaning to most expressions and comprehend the visual novel. However, for those that I can't, I am hoping to receive help here. Hopefully, with my resources, it will be few in numbers, but here goes:

The current novel is Eden's Ritter II, quite a bit of archaic wording. I will modify the sentence a bit before posting (e.g. removing none speaking sounds).

1. 余には二つの義務がある！ひとつはっ、この国をしかと治むること！
The words I looked up for shika and shikato doesn't really make sense.

2. 胸の谷間を大きく縦に引き裂かれ、激痛が走る。
Can't quite imagine the first part; the cleavage is scratched/torn along the length?

Thank you for taking the time in answering the questions in this thread. If links/resources in English/Japanese are easier as answers, I am appreciative of those too.

Frankincense said:

I look the words up at https://dictionary.goo.ne.jp/
2. 縦に = vertically, 引き裂く = to tear/rip/cut apart
I imagine a girl getting a big cut wound down along the line of the cleavage. Not sure about the context here though.

Click to expand...

Not much additional context given besides she's under attack; the preceding two lines were:
矢が突き立っているとは思えない俊敏さで、ゼノバブーン達が襲い掛かってくる。
最初の一撃は弓で弾いたが、続く二撃目をかわし損ねる。
-胸の谷間を大きく縦に引き裂かれ、激痛が走る。

The size of her chest makes it hard to imagine a claw could reach through her cushion to her torso. =3