That is weird...if you did open all the treasure chests then you should have gotten it already. It's in one the of the rooms that requires the pink key to open(the one that you can buy from shop). Is it possible that you have already gotten the item, but the upgrade did not show up? Maybe you already have the item but the upgrade requires you to upgrade other stuff first? Can you check your items again to see if you have item "書物:補給と兵站"?
allright, i'd like to talk about what other guy (kazuma) on prev page, about getting 4th wave on 1st playthrough..
actually i got both 3rd and 4th wave upgrade consecutively after clearing 30 dungeons with 100% completion (exact 30 dungeons i counted them lol)
maybe i didn't notice that i got one of them from 6th floor, but after going around clearing some dungeons, i got the notification with 2 other upgrades
you can see them below, and i have 4 waves now
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i don't consider wiki has some misses, just take this as alternate way to get them in 1st playthrough
also i didn't notice until a while ago that i've got myself a ninja room, with a new flame trap
so far i've noticed some familiar structures in enemy's dungeon such as
- obelisk, than green thingy tower (that you posted), which gives attack aura
- war council, big red mark on floor, which on previous series gave additional exp boost to room and adjacent room
- geyser/demon nest, yellow sand thingy that gives you access to summon nature mobs (slime, crawler/caterpillar, golem/gigant, and Dragon)
after reading the wiki, i've seen that dragon unit blueprint can be found on '宝箱:光翼の塔 7F'
i've really wanted to have this unit since they're extremely powerful on the previous series
just placing 3 of this unit on the entrance can wipe entire enemy squad in a split second, with their AOE breath attack which is considered as regular attack :O
maybe any of you have got your hand of this unit ?
let me know whether they're still kickass as before :D