World Trigger

A 2013 manga.

One day, an interdimensional gate opened through the skies of Japan. Through them, alien creatures initation their invasion on Earth. However, before they could go any further, they were repelled by a group of humans of mysterious origins. They become known as "Border".

Four years later, a teenage boy known as Kuga Yuuma reached the city of Mikadoshi, where the aliens entered and continue to try to enter Earth. He says he is foreign, but his lack of common sense and social skills hint at his true identity: Kuma is an alien, and his family came from the other side of the same gate the invader aliens came from.

Aside of that, the story also focus on Mikumo, a high-schooler that is also a member of "Border", which fights the aliens with the help of an Applied Phlebotinum known as "Triggers".

Tropes used in World Trigger include:

Badass Grandpa: Viza seems to be very old, but has a lot of experience in battle and can perfectly keep up with the younger guys.
Bifauxnen: Obishima is so boyish looking that Kuga mistakes her for a boy.
Brother-Sister Incest : Parodied when Shiori creates a fictional storyline for her mole molds where one is sister of another.
Combat Clairvoyance: Jin can see the future, but the way it works it's more like "calculating probabilities", with him mentioning several different futures that less or more favorable.
Eyes Always Shut: Viza never opens his eyes.
Gonk: Motokichi is drawn in a very cartoonish style.
Heroic Albino: Kuga has white skin and hair.
Jerkass: Enedra has no redeeming qualities, he spents all his time belittling and mocking earthlings and boasting about how he is superior.
Life Energy: Trion is a biological energy in humans and Neighbors. It's produced by the Trion Gland and determines a person's Trion Levels. This energy gives power to Triggers, and their output is determined by the quality of a person's Trion.
She's Got Legs: The most Fanservice this serie gets are Kirie's legs, and these are pretty legs.
Surprise Incest: Shiori treats her mole mods like they're part of a Henshin Hero show, and one of these elements she includes is the Pink one being in love with the Black one, not knowing he is her brother.