Don't know where to begin?

While ultimately it doesn't matter which arc you begin with, Cecil arc is recommended if you want my recommendation.

Alien arc (10)

This arc is different from other arcs.

This arc begins in even further future. The time is set in year 12328. It basically skips about 5 generations from year 9599. This setting has huge inspects on a lot of things. United Sol is just a record in a history book for an example.

The story starts basically anew with new characters.

[Alien arc] [1] [Gallo] [12328]

[Alien arc] [2] [Captain Cecilia] [12328]

[Alien arc] [3] [The Hope] [12328]

[Alien arc] [4] [Alucasa] [12328]

[Alien arc] [5] [The Nebula pirates] [12329]

[Alien arc] [6] [Sae the witch] [12329]

You sometimes look back the path you've walked on and recall few mistakes you've made that changed your path forever.

[Alien arc] [7] [The Saviors] [12330]

This is the beginning of “The Saviors” mini arc within Alien arc. And this story is actually a very recent addition to this arc. There are three major players in this arc. Gallo of the Gray mist is one. Captain Erika is another. And this story covers the third player.

[Alien arc] [8] [Perpetual] [12329]

It’s really hard to find a good opportunity for either Cecil(ia) or Sae to have a casual conversation. It’s why this episode was born.

This specific story existed for over decades even before the concept of the alien arc was conceived. It remained as an independent piece until I decided to stick in here with some modifications.

[Alien arc] [9] [Seven days of fire] [12330]

This is where Gallo becomes a leader instead of a mere fighter pilot. There may be what seems like plot holes in the story but they are intended.

It's 88 pages long.

[Alien arc] [10] [Fallen Leaf] [12330]

This is a standalone side story that roots itself from 'Gallo of the Gray mist' story “Seven days of fire”. This side story fills some gaps for the story.