New series tends to be cancelled if they go bad in the magazine, regardless its sales. There were series that sold 50~60k in their first volume and they were cancelled even so because of bad rankings. You cannot compare Bleach with World Trigger for obvious reasons, one is a worldwide renowned series that in its best ages almost reached 1 million of copies sold per volume, and the other is a fairly new series that sells 150k at best. Not so long ago we discusses here Bleach situation, it will not be cancelled, probably, but there will be a moment where the editors will say to Kubo accelarate the story.
We hope that it go higher in the next chapters. You guys are mistaking what I'm saying, I said "if it continues it may be cancelled", it is true because it doesn't have protections such as Bleach has, it is not a successful series with more than 10 years running. If the editors realize that the anime didn't have the expected reaction and that the rankings are too low, it will be cancelled like any other series in similar situation.
Since you talked about random characters, I shall give my opinion about them. The number of characters itself and the number without background that have in World Trigger is way too big IMO. Putting a dozen of characters aside, we don't know anything about the rest. It's hard to find interesting a fight of a character you don't know anything about,
True, WT only exists for a year and some. Hasn't even been translated into german yet, else I would buy it here...
I am also hoping that the chapters themselves can pull the manga out of the bottom five. If I get the math correctly then those past two weeks had either been about 70/71 or 71/72, in any case 71 was part of it. And as you critized it was about only side-characters so to say, people we know mostly their names, looks and position of. That doesn't mean though that the chapter was bad, the fight was good, the analyzing part to get to the victory was good (and compared to Bleach ch.602...let's not compare those...), the whole bloody murder was good, but it was done by people readers, even if they want to, can't really much care about. It is easier to care about Yuuma, Osamu and Chika or Jin and Miwa as you know where they are coming from, what motivation drives them and what they want to get in the future by their actions. Like Miwa for example, a single chapter of him fighting is already more interesting due his personality than a chapter with a bunch of characters fighting you haven't seen or heard much of (yet) as we know he hates the neighbors with a passion due them kiling his big sister for her trion and that he wants more power to be able to get revenge on them. That and he stays true to his hatred, being distrusting and unpolite to Yuuma, our neighbor MC. He just offers "more" to his fights due him being him and us knowing him thanks to past chapters expalining stuff about him.
But I myself don't see it as a weakness that Ashihara has introduced so many characters. Midorikawa was seen as early as chapter and we didn't thought much of him, neither knowing his name nor position. Later we find out that he is actually a high-ranked A agent who will most likely become a rival to Yuuma in the future Rank wars as well as that he is a "talented puppy excited to show off his skills", overconfident, a bit mean-spirited and a Jin-obsessed fan. And I am sure we get to see the other twos who had greeted Jin back then with a "hello there, Jin-san" and "Ugh, Jin-san" after the invasion arc and find out more about those as well. It's like real life where you cannot get to know everything about a person once you meet them. We have to get there bit by bit. Granted it would have been darn nice to get to see a flashback of Enedra to give him more flesh to his character than a raging rascist powermonkey or to see more of General Manager Shinoda's personality or past life, but then the Invasion arc would have become even longer and it is already very long for such a young manga. I might remember wrong but I'm pretty sure we didn't had such long arcs for One Piece, Naruto and Bleach till they hit 90-100 chapters. They had many smaller arcs than one big one after a short one.
Another problem of Ashihara is his manga's location so to say. In One Piece we also got tons of characters as to many we don't know much but their names, looks and positions, but it doesn't matter as Luffy and co are always traveling so in one travel we can get to learn that Vivi is no bounty hunter but a princess or that even somebody as weird as Franky can become atrusted member of Luffy's crew. In WT for the beginning there won't be much traveling with our MCs for good reasons and the city and HQ itself aren't that big either. In other words Ashiahra is forced to show people who will matter later but he has not yet the time to flesh them much more out than show their faces, position and maybe some stuff like some guy liking to smoke or to act some sort of comedy clown. However he still hold a back a lot, even in this arc for future ones, like Amon's Black trigger power or the Top5 of the B teams who surely will become a problem for Osamu and co when they wanna reach A level.
I find it still a big shame that so many juicy/interesting infos are found out via interviews, like Jun and Konami being cousins or the Chano-kun, the leader of B18 aka a weak B team, actually being a girl which really surprised me. And we found nothing like that out via the manga. Though it is understandable, you can build up the world and characters only so much with 80 chapters, especially when, by now, half of them are action chapters with lots of battle and tactics. I might have to reread, but I am pretty sure that in terms of World building WT has done in 80 chapters more than OP/Naruto and Bleach did in 100 but in terms of fleshing characters out those three have shown "more" in 80 chapters as they focused on a smaller group. Imagine Oda trying to include Robing and Franky into Luffy's crew as early as in 80 chapters together wtih Zoro and Nami and Sanji and what not, THAT development would have ended pretty badly most likely.
Well, anyway chapter 72 or 73 whichever gets ranked next probably won't rank much higher due them again being about side-characters fighting the big bad guys, 72 has the advantage of the murder and 73 of the start of the count-down to the crossraod future, but I can't see those being good enough to get over the "okay, the fights are nice and all but WHO are those people?"-confusion. XD
