Hi Kazuki,
Generally The schema used by DXC is owned by DXCUser and while creating HTTP connection to HANA, we use the DXCUser's password
So if you change the DXCUser password may be you might have to update the password in the HTTP Connection also that is used to connect your HANA system to your Business Suite System
For changing password in Business Suite system, use transaction SM59 and open the connection that was made
Then in that connection goto Logon and Security tab and update the DXC user's password
You can also Refer Note 1583403 - Direct extractor connection to SAP HANA