Well, unless your sectional sofa is held together by YouTube's privacy policy in Japanese, the provided context isn't going to get us very far. So, let's set that aside and tackle this furniture puzzle with some good old-fashioned know-how.
Ah, disassembling the great sectional sofa. It's a modern rite of passage, a true test of strength, spatial reasoning, and your relationship with whomever you've roped into helping. First, you'll need to go on a treasure hunt. The prize you seek is the connecting hardware that secretly holds your furniture behemoth together. This usually involves removing all the cushions and peering into the dark abyss where the sections meet. You might also need to tilt a section back to get a good look at its underbelly.
Most sectionals use a simple but brutish system of metal connectors. The most common type is a fork-and-post or "gator clip" system. One sofa piece will have a V-shaped or U-shaped bracket with teeth, and the adjoining piece will have a metal post for it to grab onto. To release this surprisingly stubborn grip, you and a partner need to lift one section straight up, vertically, away from the other. Don't try to pull them apart horizontally; you'll just end up in a frustrating tug-of-war with an inanimate object. It's an upward lift, like you're presenting it as a sacrifice to the moving gods.
If a mighty upward heave doesn't work, you might have a different kind of connector, perhaps one with a lever or a latch that needs to be released. If you find no obvious hardware, it's possible the pieces are simply held together by bolts. In that case, you'll need to grab a wrench and get to work. Once you've successfully uncoupled the pieces, you'll have a collection of manageable, albeit still heavy, parts. Congratulations, you have conquered the beast. Now you just have to figure out how to put it all back together again.
