Board Thread:Touken Ranbu Pocket/@comment-70.199.1.31-20160325202433/@comment-26093926-20160325215237

First you'll need Koushuu gold from the shop. Press the '+' button beside the gold coin and number then proceed answering yes ( はい ) to the popups. It will ask you for your age after, this limits how much you will be able to spend on the game per month. Select the amount you want. Payment methods will vary. You'll need at least 10 koushuu gold to buy the repair room extention.

Second, head to the shop through the big green menu button on the top right  then go to Shop ( 万屋 ). The bottom last yellow tab will show you the room expansions where you can buy the Repairs Extension Worker (手入部屋). Buy it

I do recommend if you can sync your mobile account to PC, instructions are in the Touken Ranbu Pocket page, that you follow the free 500 DMM points tutorial in the Shop page to basically pay for the extension without spending money

good luck!