Onee-san No First Lesson [English], by Dunga

Ah, this is a new mangaka we’ve got there, with a very original art style frequently disrespecting anatomy, but making up for it with enthusiam and strongly impactful traits based on crude genitalia, dark lines, strong contrasts, and lovely massive knockers.
The story itself is more stereotypical, vanilla, two youngsters at last daring to become lovers, etcetera, it was still making us feel good inside while reading

I think we owe the release to Kishidakyoudan, thank you!

And now, the download & gallery links

Open the Complete Pictures Gallery

Or you can also use the Alternative:
Zip Mirror #1 – or – Zip Mirror #2