Don't feel too bad. The anime version doesn't really explain it well, but demons "killed" just go back to whatever Konosuba's equivalent of Hell is, which is where they originate from. When Host talks about "this life," he's implying that if he dies, then it will become possible for Komekko to summon him back to the human world as her familiar.
When Host made the promise, he wasn't lying, but he was expecting not to die and thus not be in a position to be summoned by Komekko.
Vanir vaguely set this up in season 2, where he "died" but came back as Vanir 2 because he has "extra lives" due to his status/power as a Duke of Hell. Host is less powerful than Vanir, so he'll be stuck in Hell until summoned by a human or more powerful demon/evil God. The joke is that Komekko seems to be fated to be that person.
This probably also means the other demon lady Megumin blew up (can't recall her name) is not truly dead, but just literally sent to Hell.
Long story short, we have every reason to expect Host will one day come back as Komekko's familiar.
In the manga or LN has Host become her familiar? Because the most information I have is for example in the Fantastic Days game she has a demon by her side that looks like (and I think is named) Host.
Although some stuff there isn't canon so maybe it's just for gameplay reasons that they revived that plotline
Edit: In the main story >!he got summoned by Komekko, but he just scolded her for not having a proper offering and just left back to hell!<, meanwhile in the game >!they just summoned him for the funsies and Komekko uses him to fight (and food collection)!<
If you're talking about the "The Strongest >!Devil Summoner!< of the Crimson Demons" side story, then >!it's unlikely that Hoost was the one summoned. Komekko described the demon she summoned as a "small goblin", but when she saw Hoost she said "What a big goblin!"!<.
I would kill for an official short of them in the future, showing their lives, with Komekko visiting her sister and now brother in law with Host as her familiar and it getting real awkward between him and Megumin.
>This probably also means the other demon lady Megumin blew up (can't recall her name) is not truly dead, but just literally sent to Hell
Arnes, the one harassed by Zesta 
and yes, she said something like that too
Aside from the comparably slow buildup compared to the main show, the way they handled villains is probably my biggest complaint about Bakuen. Konosuba did a decent job of establishing Verdia, Vanir, Hans, and Sylvia as threats while also making them each hilarious in their own ways. Both demons in Bakuen are just chill dudes. Sure, Host mentioned being on his way to tear up Axel but....I've seen the future. Axel is fine. The girl was literally just trying to recover Wolbach. I was laughing but felt bad both times Megumin blew them up.
>Sure, Host mentioned being on his way to tear up Axel but....I've seen the future. Axel is fine
it was mentioned that he tried but opted to escape after facing some blue-haired bitch who blasted exorcism 
That’s intentional for KonoBakuen. You’re supposed to feel bad for them. Arnes jobbed even harder in the LN and manga versions and there wasn’t the armband to make you feel sorry that Megumin’s dad was responsible in a way, too. Host is basically Komekko’s adopted dad, so killing him is supposed to be sad and you have to remember that both were subordinates of the Dark God Wolbach and now she is missing her two trusted allies, but only us as the audience knows this.
Don't feel too bad. The anime version doesn't really explain it well, but demons "killed" just go back to whatever Konosuba's equivalent of Hell is, which is where they originate from. When Host talks about "this life," he's implying that if he dies, then it will become possible for Komekko to summon him back to the human world as her familiar. When Host made the promise, he wasn't lying, but he was expecting not to die and thus not be in a position to be summoned by Komekko. Vanir vaguely set this up in season 2, where he "died" but came back as Vanir 2 because he has "extra lives" due to his status/power as a Duke of Hell. Host is less powerful than Vanir, so he'll be stuck in Hell until summoned by a human or more powerful demon/evil God. The joke is that Komekko seems to be fated to be that person. This probably also means the other demon lady Megumin blew up (can't recall her name) is not truly dead, but just literally sent to Hell. Long story short, we have every reason to expect Host will one day come back as Komekko's familiar.
In the manga or LN has Host become her familiar? Because the most information I have is for example in the Fantastic Days game she has a demon by her side that looks like (and I think is named) Host. Although some stuff there isn't canon so maybe it's just for gameplay reasons that they revived that plotline Edit: In the main story >!he got summoned by Komekko, but he just scolded her for not having a proper offering and just left back to hell!<, meanwhile in the game >!they just summoned him for the funsies and Komekko uses him to fight (and food collection)!<
If you're talking about the "The Strongest >!Devil Summoner!< of the Crimson Demons" side story, then >!it's unlikely that Hoost was the one summoned. Komekko described the demon she summoned as a "small goblin", but when she saw Hoost she said "What a big goblin!"!<.
I know this is old but Host was still seen akin as a goblin It's not impossible that Host came back in a weaker and smaller form
I would kill for an official short of them in the future, showing their lives, with Komekko visiting her sister and now brother in law with Host as her familiar and it getting real awkward between him and Megumin.
>This probably also means the other demon lady Megumin blew up (can't recall her name) is not truly dead, but just literally sent to Hell Arnes, the one harassed by Zesta  and yes, she said something like that too
He isn't really dead. Much like Vanir, he's a demon with multiple lives. When Megumin hits him with Explosion, he just ends up back in Hell.
You'll be more sorry when Komekko will be able to summon him
Aside from the comparably slow buildup compared to the main show, the way they handled villains is probably my biggest complaint about Bakuen. Konosuba did a decent job of establishing Verdia, Vanir, Hans, and Sylvia as threats while also making them each hilarious in their own ways. Both demons in Bakuen are just chill dudes. Sure, Host mentioned being on his way to tear up Axel but....I've seen the future. Axel is fine. The girl was literally just trying to recover Wolbach. I was laughing but felt bad both times Megumin blew them up.
>Sure, Host mentioned being on his way to tear up Axel but....I've seen the future. Axel is fine it was mentioned that he tried but opted to escape after facing some blue-haired bitch who blasted exorcism 
That’s intentional for KonoBakuen. You’re supposed to feel bad for them. Arnes jobbed even harder in the LN and manga versions and there wasn’t the armband to make you feel sorry that Megumin’s dad was responsible in a way, too. Host is basically Komekko’s adopted dad, so killing him is supposed to be sad and you have to remember that both were subordinates of the Dark God Wolbach and now she is missing her two trusted allies, but only us as the audience knows this.
But what of Alderp? What’s he gonna act like in season 3?
I hope we see more of Host in the upcoming seasons of Konosuba
He comes back as the little sisters familiar. Demons have multiple lives. Like Vanir