Like a Dragon: Infinite Wealth

Achievement is unlocked after the 5th drink link with Namba. Drink links are unlocked every 10 bond levels, with the last becoming available after bond level 50.



I hit bond level 50 with Namba during chapter 10. I Completed all of his Bond Bingo's in earlier chapters and was only at level 43ish during chapter 10. I grinded out the last levels via karaoke playing the same 1 song that Namba sings. You might get this earlier in your playthru, YMMV based on how many battles/table talks/party chats you've done already.

You can also increase you bond level via table talks, party chats and some mini games. Karaoke does fantastic for this, especially if the character whose bond you are trying to raise is the one who is singing.