Two months before updating this. Well, whatever.
Welcome to Kanpokanyonen
Kanpokanyonen comes from Adarian's "Kanpo" (Field) and "Kanyonen" (Cannons), so the name would translate to "Field of Cannons". When Nichiuri was an actual fortified city, in the 18th and 19th century, this was the area where cannon shots could reach from the turrets in the city walls and the Colonial Castle. All this area was restricted from residential building, as any house could be in risk in being shot by a cannon in case of a siege of the city. The fields even reached the other side of the river, where some defensive structures were built. Now what's left is the East tower, just by the river in the southern "Ensanche" quarter. As the 19th century was going and the city inside the walls became more and more crowded, some tried to establish small markets outside the wall gates, trying to develop outwards. The most prominent example was the Nishi Street Market, which developed into a residential slum along the road that led to the gate. Part of it survives to this day thanks to being one of the last attempts at building outside the gate before the turrets were disarmed in the late 19th century and the whole place became urbanized.
Some of the people who wanted to get out of the overcrowded city walls, however, moved to a nearby town along the Sakura road, north of the city. That small town was spared of disappereance because it was just outside of the cannon range, and it quickly developed into a major town. We now know it as Sakuramachi.
In the late 19th century, the city council finally gave up to the pressions of citizens to allow building in the Kanpokanyonen area. Soon after, tens of projects arrived at the town hall to discuss about the plan of urbanization of the area. The final plan approved was the one that arrived to our present day, but severely expanded outwards.
Kanpokanyonen and Aviation
The plan dictated that two big parks should be built in the district. One along the river in the east, and one along the railways (newly constructed by then) in the west. The western park was planned to be build in the 1910s, as the city started to expand westwards, but then, the owner of the lands declined to lease the place to the public, while he was constructing something he saw in western Uletha a few years ago. He wanted to build an airfield.
And so he did, in 1915, the first plane took off Adarian lands, in the Kanpokanyonen aviation field. The place started to be surrounded by buildings soon enough, and some operations moved to the 4th of May airport, open in the next decade in the marshes of the Yolis river mouth. However, the place was operational as an airport for many years later, until the 1960s, and it still holds aeronautical activities to this day. It also was a very prominent place in the 1932 world fair, which was taking place at the fairgrounds just in front of it.